effects of nutritional and environmental factors on physiological responses and semen...

EFFECTS OF NUTRITIONAL AND ENVIRONMENTAL

FACTORS ON PHYSIOLOGICAL RESPONSES AND

SEMEN CHARACTERISTICS OF DESERT RAMS

BY

SUHAIR SAYED MOHAMMED A/ ALRAHMAN (B.V.Sc., University of Cairo, M.V.Sc., University of Khartoum)

Thesis submitted in fulfillment of the requirement of the degree of

Ph.D. in Veterinary Science in Animal Physiology

Supervisor

Dr. Abdalla M. Abdelatif

(B.V.Sc , M.V.Sc., Ph.D.)

Department of Physiology

Faculty of Veterinary Medicine

University of Khartoum

November, 2005

DEDICATION

To the soul of my

dear younger brother

Ustaz Omer Sayed, whose

love, sympathy and

assistance brought this

work to the end.

fâ{t|Ü

Acknowledgements

Iam greatly indebted to my supervisor Dr. Abdalla M. Abdelatif

with sincere thanks for his continuous help and guidance and patience

throughout this study.

Iam particularly grateful to Dr. Faisal H. Ibrahim, Minister of

Agriculture, Animal Resources and Irrigation – Khartoum State and Prof.

Ali M. Abdelmagid for their financial support. Also special thanks are

due to the administration of Bahr Elghazal University for granting me

necessary time and fund to fulfil this work.

Due thanks and gratitude are to my brother Ustaz Mohammed

Sayed , whose presence by my side throughout this study helped me to

overcome all accompanied hinders and events . My thanks are

extended to Ustaz Mohamed E. Alnageeb, Ustaz Ashwag Alnour,

Hussien A. El Gadir, Staff of Department of Physiology and staff of

Department of Biochemistry–Soba Research Centre for their assistance

during the study. Special thanks are to Dr. Shawgi M. Hassan and Ustaz

Alwasila Mukhtar for their assistance in the statistical analysis, Ustaz A.

Hamed A. Rahim for typing this thesis.

Finally Iam most grateful to my family, sisters and brothers for

their endless emotional support .

ABSTRACT

The studies were conducted to investigate the effects of certain

nutritional and climatic factors on thermoregulation, blood composition

and semen characteristics of Desert rams .The experimental design

included evaluation of the effects of lowering the level of feeding

Lucerne hay to 66% (medium) and 33% (low) at libitum level on

thermoregulation, blood metabolites and semen characteristics under

typical winter and summer thermal environments. Also the effects of

exposure of Desert rams to solar radiation and exhaustion test , performed

by frequent ejaculation, on thermoregulation, blood metabolites and

semen characteristics were evaluated. The responses of rams to shearing

and fasting during winter and summer conditions were also investigated.

Feeding 33% at libitum level of lucerne hay during winter and

summer resulted in lowering of body weight (BW) and scrotal

circumference (SC) of Desert rams. The rectal temperature (Tr) decreased

significantly in the morning and afternoon and showed a diurnal pattern.

The respiration rate (RR) was significantly lowered during the morning.

Serum total protein concentration was significantly lower during winter

and serum albumin concentration was significantly lower in both seasons

in response to feed restriction. In both seasons, feed restriction

significantly lowered ejaculate volume, sperm individual motility and

sperm concentration. During summer , sperm mass motility and live

sperm percentage were significantly lower and abnormal sperm

percentage was significantly higher.

Exposure of Desert rams to solar radiation significantly increased

morning rectal temperature (Tr) in the second week and afternoon value

of (Tr) in the first week of the experimental period. The respiratory rate

(RR) in the morning and afternoon was significantly higher in the last

week of the experimental period. In the last two weeks of the

experimental period , the ratio of neutrophils was significantly lower and

that of monocytes was significantly higher. The ratio of eosinophils was

significantly lower in the last week of the experimental period compared

to the value obtained for the shaded group. Compared to the control the

unshaded rams also had significantly higher serum total protein

concentration in the third week of the experimental period, while the

concentration of serum albumin was significantly lower in the second

week of exposure to solar radiation.Serum urea and plasma glucose levels

were significantly lower in the third week of the experimental period. The

ejaculate volume, sperm mass and individual motility, sperm

concentration and live sperm percent were significantly lower in response

to solar heat stress while abnormal sperm percent was significantly

higher. The exhaustion test of the rams for 3 consecutive days during

exposure to solar radiation resulted in lower PCV level in the last day of

the experimental period and low total leukocyte count (TLC) in the first

day. The serum total protein level was significantly lower in the first and

second day, and the plasma glucose level was significantly increased in

the second day. For seminal traits, the sperm individual motility, sperm

cell concentration and abnormal sperm percent were significantly lower

in response to exhaustion test and heat stress ;while the percent of live

sperm was significantly higher. Exhaustion of shaded rams lowered PCV

level during the three days of the experimental period, total leukocytes

(TLC) in the first and second days and the percent of monocytes in the

first day. In shaded rams exhaustion test significantly lowered the

concentration of serum total protein in the first and second day of the

experimental period; while the concentration of serum urea and plasma

glucose increased in the last and first day of the experimental period

respectively. Exhaustion of shaded rams significantly lowered the

ejaculate volume in the three days, sperm individual motility in the first

and third day and sperm concentration in the first and second day of the

experimental period .The percent of abnormal sperm was significantly

higher in the second day .

Shearing of rams significantly lowered rectal temperature (Tr) in

the morning during winter and summer and in the afternoon during

summer only. The respiration rate (RR) was significantly lower in

response to shearing in the afternoon during winter and summer. The

plasma glucose level was significantly higher during winter in shorn

rams compared to summer values. The sperm mass motility was

significantly lower during summer compared to winter and the sperm

individual motility was significantly lower in both seasons in response to

shearing. Compared to respective values obtained for the control group,

fasting of shorn rams resulted in significantly lower ratio of lymphocytes

during both seasons and higher monocytes ratio during summer.

However, in both groups the ratio of neutrophils and eosinophils was

significantly higher during summer and the ratio of monocytes was

significantly lower. The serum concentrations of total protein and urea

were significantly higher in winter in shorn fasted rams compared to

values obtained for the unshorn. During summer, fasting of shorn rams

significantly lowered serum urea concentration. In both seasons, plasma

glucose concentration was significantly higher in fasted shorn rams

compared to unshorn, and it was significantly lower during winter post-

fasting in shorn rams compared to values obtained during summer.

The findings of these studies showed that feed restriction

induced significant changes in the physiological responses of Desert

rams. The results indicated that Desert rams can acclimatize on exposure

to direct solar radiation. However, thermal stress negatively affected

scrotal thermoregulatory mechanism and consequently seminal traits.

Exhaustion of unshaded rams did not exert an additional stressful

condition. Shearing of Desert rams had positive influences on

thermoregulation during both seasons and negative influences on sperm

motility.

LIST OF CONTENTS

Page

DEDICATION……………………………………………..………………………………………….. i

ACKNOWLEDGEMENTS………………………….…………………………………………… ii

ABSTRACT …………………………………………………………………………………………… iii

LIST OF CONTENTS………………………..………………..…………………………………… v

LIST OF TABLES………………………………….……………………………………………… xv

CHAPTER ONE: GENERAL INTRODUCTION ………......…………………… 1

1.1 Economic importance of sheep in

Sudan………………………………………..…… 1

1.2. Reproductive performance of sheep under tropical conditions……………… 2

1.3 Effects of nutritional factors………...……………………………………………………… 3

1.3.1. Thermoregulation………………….………………………………………………………… 3

1.3.2 Blood metabolites………………………………………………………………….………… 5

1.3.3 Semen characteristics……………..………………………………………………………… 6

1.4 Effects of thermal factors on male animals……………………………...………… 10

1.4.1 Effects of seasonal changes in thermal environment………………….……… 10

1.4.1.1 Thermoregulation…………………………………………………………….…………… 11

1.4.1.2 Blood composition……………………………………………………………..………… 12

1.4.1.3 Semen characteristics ………………………………...…………………………………

1.4.2 Effects of exposure to solar radiation……………………………………..…………

13

15

1.4.2.1 Thermoregulation………………………………………………………………………… 16

1.4.2.2 Blood composition……….………..……………………………………………………… 16

1.4.2.3 Semen characteristics………………………………………..…..……………………… 18

1.4 .3 Effects of thermal environment and shearing……….…………….…………… 19

1.4.3.1 Thermoregulation……………………….………………………………………………… 20

1.4.3.2 Blood composition………………………...……………………………………………… 21

1.4.3.3 Semen characteristics…………………………………..………………………………… 22

1.5 Effects of frequency of ejaculation………………………….…………………………… 22

1.5.1 Frequent ejaculation of semen and assessment of male reproductive

capacity …………………………………………………………………..……………………… 22

1.5.2 Effects of frequent ejaculation on semen characteristics…..………………… 23

1.6 Objectives …………………………….…………………………………………………………… 26

CHAPTER TWO: MATERIALS AND METHODS.......................................... 28

2.1 Experimental animals………………………….……………………………………………… 28

2.2 Housing and management…………………………………………………………………… 28

2.3. Rectal temperature (Tr) …………………...………………………………………………… 30

2.4 Respiration rate (RR) ………………….……………………………………………………… 30

2.5 Body weight (BW) …………………..………………………………………………………… 30

2.6 Scrotal circumference (SC) ………………………………………………………………… 30

2.7 Collection of samples………………….……………………………………………………… 30

2.7.1 Blood samples…………………………….…………………………………………………… 30

2.7.2 Semen samples………………………….…………………………………………………… 31

2.8 Analyses of samples………………...………………………………………………………… 31

2.8.1 Blood samples………………………………………………………………………………… 31

2.8.1.1 Packed cell volume (PCV)…………………………...................................................... 31

2.8.1.2 Leukocytic indices...................................................... ....................................................... 32

2.8.1.2.1 Total leukocyte count.(TLC) .................................................................................... 32

2.8.1.2.2 Differential leukocyte count (DLC) ..................................................................... 32

2.8.2 Serum samples...................................................................................................................... 32

2.8.2.1 Serum total

protein.............................................................................................................. 32

2.8.2.2 Serum albumin..............................................................

....................................................... 32

2.8.2.3 Serum

urea............................................................................................................................... 33

2.9 Plasma glucose..............................................................

....................................................... 33

2.10 Semen samples..............................................................

....................................................... 33

2.10.1 Appearance.....................................................................

....................................................... 33

2.10.2 Ejaculate

volume............................................................................................................... 34

2.10.3 Sperm mass motility.......................................................

............................................. 34

2.10.4 Sperm individual

motility............................................................................................ 34

2.10.5 Sperm cell

concentration........................................................................................... 34

2.10.6 Incidence of live

sperm................................................................................................. 35

2.10.7 Incidence of abnormal

sperm.................................................................................... 35

2.10.8 Hydrogen ion concentration (pH)

....................................................................... 35

2.11 Climatic

measurements.......................................................................................................... 36

2.12 General experimental

plan................................................................................................... 36

2.13 Statistical analysis.............................................................

....................................................... 38

CHAPTER THREE: EFFECTS OF LEVEL OF FEEDING LUCERNE

HAY AND SEASONAL CHANGES IN THERMAL

ENVIRONMENT ON THERMOREGULATION,

BLOOD METABOLITES AND SEMEN

CHARACTERISTICS................................................................................. 39

3.1 Introduction....................................................... ............................................................................... 39

3.2 Experimental procedure.............................. .............................................................................. 41

3.3. Results....................................................... ........................................................................................ 43

3.3.1. Body weight ( BW) .............................................................................................................. 45

3.3.2. Scrotal circumference (SC) ..............................................................................................

3.3.3 Thermoregulation .....................................................................................................................

45

45

3.3.3.1 Rectal temperature ( Tr) ................................................................................................... 45

3.3.3.2 Respiration rate (RR) ........................................................................................................ 49

3.3.4 Blood metabolites ................................................................................................................ 49

3.3.4.1 Serum total protein............................................................................................................ 49

3.3.4.2 Serum albumin....................................................... ............................................................... 54

3.3.4.3 Serum urea...................................................................... ....................................................... 54

3.3.4.4 Plasma glucose...................................................................................................................... 54

3.3.5 Semen characteristics............................................................................................................. 58

3.3.5.1 Ejaculate volume....................................................... ....................................................... 58

3.3.5.2 Sperm mass motility.......................................................................................................... 58

3.3.5.3 Sperm individual motility............................................................................................... 58

3.3.5.4 Sperm cell concentration................................................................................................. 62

3.3.5.5 Incidence of live sperm ............................................................................................... 62

5.3.5.6 Incidence of abnormal sperm .................................................................................. 62

3.4 Discussion................................................. ............................................................................. 66

3.4.1. Body weight and scrotal circumference................................................................. 66

3.4.2. Thermoregulation..................................................................................................................... 68

3.4.3. Blood metabolites.................................................................................................................... 71

3.4.4. Semen characteristics............................................................................................................ 73

3.5 Summary.............................................. .................................................................................... 80

CHAPTER FOUR: EFFECTS OF EXPOSURE TO SOLAR RADIATION ON

THERMOREGULATION, BLOOD COMPOSITION AND

SEMEN CHARACTERISTICS .... 82

4.1 Introduction....................................................... ............................................................................... 82

4.2 Experimental procedure............................................................................................................. 83

4.3. Results....................................................... ......................................................................................... 86

4.3.1 Effects of exposure to solar radiation........................................................................... 86

4.3.1.1 Thermoregulation................................................................................................................. 86

4.3.1.1.1 Rectal temperature (Tr) ............................................... ................................................ 86

4.3.1.1.2 Respiration rate(RR) .................... ............................................................................... 90

4.3.1.2 Blood composition....................................................... ....................................................... 90

4.3.1.2.1 Packed cell volume (PCV) ......................................................................................... 90

4.3.1.2.2 Leukocytic indices........................................................................................................ 94

4.3.1.2.3 Serum total protein............................... ........................................................................ 97

4.3.1.2.4.Serum albumin....................................................... ........................................................... 97

4.3.1.2.5 Serum urea....................................................... .................................................................... 97

4.3.1.2.6 Plasma glucose......................................... ......................................................................... 101

4.3.1.3 Semen characteristics....................................................... .................................................. 101

4.3.1.3.1 Ejaculate volume....................................................... ....................................................... 101

4.3.1.3.2 Sperm mass motility...................................................................................................... 101

4.3.1.3.3 Sperm individual motility......................................................................................... 105

4.3.1.3.4 Sperms cell concentration............................................................................................ 105

4.3.1.3.5 Incidence of live sperm................................................................................................ 105

4.3.1.3.6 Incidence of abnormal sperm.................................................................................. 109

4.3.1.3.7 Semen pH....................................................... .................................................................... 109

4.3.1.4 Scrotal circumference (SC) ........................................................................................... 109

4.3.2 Effects of exposure to solar radiation and exhaustion test........................... 113

4.3.2.1 Blood composition....................................................... ..................................................... 113

4.3.2.1.1 Packed cell volume(PCV)............................................................................................ 113

4.3.2.1.2 Leukocytic indices....................................................... ................................................. 113

4.3.2.1.3 Serum total protein....................................................... ................................................ 121

4.3.2.1.4 Serum albumin....................................................... .......................................................... 121

4.3.2.1.5 Serum urea....................................................... .................................................................... 125

4.3.2.1.6 Plasma glucose....................................................... ........................................................... 125

4.3.2.2 Semen characteristics.......................................................................................................

4.3.2.2.1 Ejaculate volume .............................................................................................................

130

130

4.3.2.2.2 Sperms mass motility............................................ ....................................................... 130

4.3.2.2.3 Sperms individual motility......................................................................................... 135

4.3..2.2.4 Sperms cell concentration ......................................................................................... 135

4.3.2.2.5 Incidence of live sperm ............................................................................................... 140

4.3.2.2.6 Incidence of abnormal sperm.................................................................................. 140

4.3.2.2.7 Semen pH............................................................................................................................. 145

4.4 Discussion....................................................... ............................................................................... 149

4.4.1 Exposure to solar radiation 149

4.4.1.1 Thermoregulation 149

4.4.1.2 Blood composition 151

4.4.1.3 Semen characteristics 155

4.4.2 Exposure to solar adiation and exhaustion test 160

4.4.2.1 Blood composition 160

4.4.2.2 Semen characteristics 163

4.5 Summary................................ ....................................................................................................... 167

CHAPTER FIVE: EFFECTS OF SEASONAL CHANGES IN 171

THERMAL ENVIRONMENT AND SHEARING ON

THERMOREGULATION, BLOOD CONSTITUENTS

AND SEMEN CHARACTERISTICS................................................

5.1 Introduction....................................................... ............................................................................... 171

5.2 Experimental procedure.................................................... ....................................................... 173

5.3 Results....................................................... ......................................................................................... 177

5.3.1 Effect of season on the responses to shearing....................................................... 177

5.3.1.1 Thermoregulation....................................................... ....................................................... 177

5.3.1.1.1 Rectal temperature(Tr) ................................................................................................. 177

5.3.1.1.2 Respiration rate(RR) .................................................................................................... 180

5.3.1.2 Blood composition............................ ................................................................................ 180

5.3.1.2.1 Packed cell volume(PCV) .......................................................................................... 180

5.3.2.2 Leukocytic indices....................................................... ....................................................... 180

5.3.1.2.3 Serum total protein....................................................... ................................................. 185

5.3.1.2.4 Serum albumin....................................................... .......................................................... 185

5.3.1.2.5 Serum urea................................................................... ....................................................... 185

5.3.1.2.6 Plasma glucose........................................................... ....................................................... 190

5.3.1.3 Semen characteristics....................................................... .................................................. 190

5.3.1.3.1 Ejaculate volume....................................................... ....................................................... 190

5.3.1.3.2 Sperm mass motility....................................................... ............................................. 190

5.3.1.3.3 Sperm individual motility......................................................................................... 190

5.3.1.3.4 Sperms cell concentration........................................................................................... 195

5.3.1.3.5 Incidence of live sperm............................................................................................... 195

5.3.1.3.6 Incidence of abnormal sperm................................................................................... 195

5.3.1.3.7 Semen pH....................................... ...................................................................................

5.3.1.4 Scrotal circumference (SC).........................................................................................

195

195

5.3.2 Effects of season, shearing and fasting on blood composition …........ 201

5.3.2.1 Packed cell volume(PCV) ........................................................................................... 201

5.3.2.2 Leukocytic indices.................................. …...................................................................... 201

5.3.2.3 Serum total protein.................................................. ....................................................... 205

5.3.2.4 Serum albumin.......................................................... .......................................................... 207

5.3.2.5 Serum urea......................................................... .................................................................... 207

5.3.2.6 Plasma glucose.......................................................... .......................................................... 207

5.4. Discussion....................................................... ............................................................................... 211

4.5.1. Seasonal change and shearing ......................................................................................... 211

5.4.1.1 Thermoregulation .............................................................................................................. 211

5.4.1.2 Blood composition ........................................................................................................... 213

5.4.1.3 Semen characteristics ....................................................................................................... 214

5.4.2. Seasonal change, shearing and fasting ...................................................................... 216

5.5 Summary....................................................... ................................................................................... 220

CHARTER SIX: GENERAL DISCUSSION AND CONCLUSIONS…… 223

REFERENCES………………………...…………………………………………..…………………. 232

ARABIC ABSTRACT …………………………..………………………………………………

LIST OF TABLES

Table Page.

1. The chemical composition of the feeds on dry matter basis 29

2. General experimental plan………………………..……………………… 37

3. Experimental plan ……………………………...…………………………… 42

4. The mean values of ambient temperature and relative

humidity during the experimental period ……………….……… 44

5. Effect of level of feeding lucerne hay and season on the

mean body weight (BW) ……………………….………………………… 46

6. Effect of level of feeding lucerne hay and season on scrotal

circumference (SC) …………………………….…………………………… 47

7. Effect of level of feeding lucerne hay and season on rectal

temperature (Tr) at 7:00 a.m. ……………..…………………………… 48

8. Effect of level of feeding lucerne hay and season on rectal

temperature (Tr) at 2:00 p.m. …………………………….…………… 50


diurnal pattern of rectal temperature (Tr) ………………………… 51

10. Effect of level of feeding lucerne hay and season on

respiration rate (RR) at 7:00 a.m. …………………………………… 52

11. Effect of level of feeding lucerne hay and season on serum

total protein concentration……………………………………..………… 53


albumin concentration………………………………………..…………… 55


urea concentration…………………………………………………………… 56

14. Effect of level of feeding lucerne hay and season on

plasma glucose concentration………………………………………… 57

15. Effect of level of feeding lucerne hay and season on 59

ejaculate volume………………………………………………………………

16. Effect of level of feeding lucerne hay and season on sperm

mass motility (MM) ……………………………………..………………… 60


individual motility (IM) …………………………..……………………… 61


cell concentration ………………………………………………………… 63


incidence of live sperm …………………………………...……………… 64


incidence of abnormal sperm ………………………………..………… 65

21. Experimental plan …………………………………………………..……… 84

22. The prevailing climatic conditions during the experimental

period. ……………………………………………………………….…………… 87

23. Effect of exposure to solar radiation on rectal temperature

(Tr) at 7: 00 a.m. ……………………………………………………..……… 88

24. Effect of exposure to solar radiation on rectal temperature

(Tr) at 2: 00 p.m.………………………………………………………..…… 89

25. Effect of exposure to solar radiation on respiration rate

(RR) at 7: 00 a.m. …………………………………………………………… 91

26. Effect of exposure to solar radiation on respiration rate

(RR) at 2: 00 p.m. …………………………………………………………… 92

27. Effect of exposure to solar radiation on (PCV) ………… 93

28. Effect of exposure to solar radiation on total leukocytes

count (TLC) …………………………………………….……………………… 95

29. Effect of exposure to solar radiation on differential

leukocyte count (DLC) …………………….……………………………… 96

30. Effect of exposure to solar radiation on serum total protein

concentration ………………………………………………………..………… 98

31. Effect of exposure to solar radiation on serum albumin

concentration…………………………………………………………………… 99

32. Effects of exposure to solar radiation on serum urea

concentration…………………………………………………………………… 100

33. Effect of exposure to solar radiation on plasma glucose

concentration…………………………………………………………………… 102

34. Effect of exposure to solar radiation on ejaculate volume 103

35. Effect of exposure to solar radiation on sperm mass motility

(MM) ………………………………………………………………… 104

36. Effect of exposure to solar radiation on sperm individual

motility (IM) ……………………………………………………...…………… 106

37. Effect of exposure to solar radiation on sperm cell

concentration……………………………………………..………… 107

38. Effect of exposure to solar radiation on the incidence of live

sperm……………………………………………………………………… 108

39. Effect of exposure to solar radiation on the incidence of

abnormal sperm ……………………………………………………………… 110

40. Effect of exposure to solar radiation on semen pH ………….. 111

41. Effect of exposure to solar radiation on scrotal

circumference (SC) …………………………….…………………………… 112

42. Effect of exhaustion test on PCV in shaded rams…………… 114

43. Effect of exhaustion test on PCV in unshaded rams………. 115

44. Effect of exhaustion test on total leukocyte count (TLC) of

shaded rams………………………………………………………..…………… 116

45. Effect of exhaustion test on total leukocyte count (TLC) of 117

unshaded rams…………………………………………………………………

46. Effect of exhaustion test on differential leukocytes count

(DLC) of shaded rams……………………………………………………… 119

47. Effect of exhaustion test on differential leukocyte count

(DLC) of unshaded rams……………………………..…………………… 120

48. Effect of exhaustion test on serum total protein concentra-

tion of shaded rams………………………..………………………………… 122

49. Effect of exhaustion test on serum total protein of unshaded

rams……………………………………….………………………… 123

50. Effect of exhaustion test on serum albumin concentration of

shaded rams………………………………………………………………… 124

51. Effect of exhaustion test on serum albumin concentration of

unshaded rams………………………………………………………..…… 126

52. Effect of exhaustion test on serum urea concentration of

shaded rams………………………………………………….………………… 127

53. Effect of exhaustion test on serum urea concentration of

unshaded rams……………………………………………….………………… 128

54. Effect of exhaustion test on plasma glucose concentration

of shaded rams………………………………………………………………… 129

55. Effect of exhaustion test on plasma glucose concentration

of unshaded rams…………………………………………..………………… 131

56. Effect of exhaustion test on ejaculate volume of shaded

rams……………………………………………………………………………… 132

57. Effect of exhaustion test on ejaculate volume of unshaded

rams……………………………………………………………………………… 133

58. Effect of exhaustion test on sperm mass motility (MM) of

shaded rams…………………………………………………………………… 134

59. Effect of exhaustion test on sperm mass motility (MM)of

unshaded rams……………………………………………..………………… 136

60. Effect of exhaustion test on sperm individual motility (IM)

of shaded rams………………………………………………………………… 137

61. Effect of exhaustion test on sperm individual motility

(IM)of unshaded rams……………………………………………………… 138

62. Effect of exhaustion test on sperm cell concentration of

shaded rams…………………………………………………………………… 139

63. Effect of exhaustion test on sperm cell concentration of

unshaded rams……………………………………………………….………… 141

64. Effect of exhaustion test on the incidence of live sperm of

shaded rams………………………………………………………………..…… 142

65. Effect of exhaustion test on the incidence of live sperm of

unshaded rams………………………………………………………………… 143

66. Effect of exhaustion test on the incidence of abnormal

sperm of shaded rams……………………………………………………… 144

67. Effect of exhaustion test on the incidence of abnormal

sperm of unshaded rams……………………………………..…………… 146

68. Effect of exhaustion test on semen pH of shaded rams…….. 147

69. Effect of exhaustion test on semen pH of unshaded rams… 148

70. Experimental plan …………………………………..……………………… 174

71. The prevailing climatic conditions during the experimental

period………………………………………… 176

72. Effect of season and shearing on rectal temperature (Tr) at

7: 00 a.m.………………………………………………………….…………… 178

73. Effect of season and shearing on rectal temperature (Tr) at

2: 00 p.m.…………………………………………………….………………… 179

74. Effect of season and shearing on respiration rate(RR) at 181

7: 00 a.m.………………………………………………………….…………

75. Effect of season and shearing on respiration rate (RR) at 2:

00 p.m.…………………………………………………………….…………… 182

76. Effect of season and shearing on PCV…………………………… 183

77. Effect of season and shearing on total leukocyte count

(TLC) ………………………………………………………………...…………… 184

78. Effect of season and shearing on differential leukocyte

count (DLC) …………………………………………………………………… 186

79. Effect of season and shearing on serum total protein

concentration ……………………………………………………..…………… 187

80. Effects of season and shearing on serum albumin

concentration ………………………………………………..………………… 188

81. Effect of season and shearing on serum urea concentration 189

82. Effect of season and shearing on plasma glucose concen-

tration………………………………………………………………………….….. 191

83. Effect of season and shearing on ejaculate volume …………. 192

84. Effect of season and shearing on sperm mass motility

(MM) …………………………………………………...………………………… 193

85. Effect of season and shearing on sperm individual motility

(IM) …………………………………………..…………………………………… 194

86. Effect of season and shearing on sperm cell concentration 196

87. Effect of season and shearing on the incidence of live

sperm…………………………………………………………………………….… 197

88. Effect of season and shearing on the incidence of abnormal

sperm ………………………………………….…………………… 198

89. Effects of season and shearing on semen pH …………..………… 199

90. Effect of season and shearing on scrotal circumference (SC) ………………………………………………………………………..……… 200

91. Effect of season, shearing and fasting on PCV ……………… 202

92. Effect of season, shearing and fasting on total leukocyte

count (TLC) ………………………………………………………………….… 203

93. Effect of season, shearing and fasting on differential

leukocyte count (DLC) ……………………………………….…………… 204

94. Effect of season, shearing and fasting on serum total protein

concentration ……………………………….……………………… 206

95. Effect of season, shearing and fasting on serum albumin

concentration……………………………………………..…………………… 208

96. Effect of season, shearing and fasting on serum urea

concentration…………………………………………………………………… 209

97. Effect of season, shearing and fasting on plasma glucose

concentration…………………………………………………………………… 210

CHAPTER ONE GENERAL INTRODUCTION

1.1 Economic importance of sheep in Sudan

The domestic sheep (Ovis aries) are widely distributed in the Sudan.

They are characterized by high adaptive capabilities to different climatic

conditions, which include extreme thermal environments and changes in

water and nutritional requirements (Gatenby, 1986a). Compared to other

ruminants, sheep are characterized by early maturation, short

reproductive cycle, utilization of poor pastures and tolerance to drought

conditions and diseases (Ingham et al., 1990). In the tropics, sheep are

raised for meat, milk, skin and wool production (Devendra and Mcleroy,

1987; Payne, 1990).

The Sudan which lies wholly within the tropics is characterized by

different climatic and ecological systems; it possesses some of the major

essentials for successful development of sheep industry which include a

high productive performance. Sheep are raised mainly by nomads; most

of them tend to have a semi-residential system, while small flocks also

exist under transhumance system (Elamin, 1975). In the wet season,

sheep utilize natural pastures and during the dry season they migrate in

pursuit of water and grazing areas (Atabani, 1966; Mohammed, 1989). The indigenous sheep population, which is estimated at 47 millions, are

classified into ecotypes, Desert, Nilotic, Arid Upland and Arid Equatorial sheep (Mcleroy, 1961a,b; Devendra and Mcleroy, 1987). Desert sheep constitute more

than 60% of the sheep population, and they are strictly confined to northern Sudan and semi-arid climatic zones (Atabani, 1966). The most recent survey indicates

that the live sheep and exported mutton represent the highest contribution compared with other species of livestock (Ministry of Animal Resources Annual

Report, 2001), and their contribution to the national economy is well pronounced. The Desert sheep is designated as the most important breed in mutton and milk

production in Sudan. They comprise the majority of live sheep export and constitute an important source of local meat consumption (Muffarih, 1991). The

annual live exported sheep is about one million and the exported mutton is about 4 thousand tons and the locally consumed mutton is more than 11 million heads per

year. The annual export of sheep hide is about 2.5 millions pieces (Elkhidir et al., 1998).

The sheep production in Sudan is influenced by many constraints

other than genotypic factors; due to seasonal migrations of pasturalists,

climatic and nutritional factors constitute major hindrances. The drought

conditions usually result in poor pastures, low productivity and great

losses (Suleiman, 1989).

As sheep in Sudan have high contribution to national economy, it

is worth studying factors that retard their productive and reproductive

potentials. The studies designed to investigate the effects of nutritional

and thermal factors on physiological adaptation and reproductive

performance could yield useful scientific information needed for

upgrading productivity.

1.2. Reproductive performance of sheep under tropical conditions

In the tropics, sheep reproduction is below their genetic potentials,

due to the harsh environment and substandard managemental system

(Devendra and Mcleroy, 1987). Tropical sheep breeds do not exhibit a

seasonal breeding pattern; they are able to breed throughout the year

(Devendra and Mcleroy, 1987; Jainudeen and Hafez, 2000). Their

reproductive performance is influenced by genetic potentials, thermal

environment and nutritional factors (Hafez, 1968; Grell, 1977; Gerlach

and Aurich, 2000).

Rams attain sexual maturity at 5-10 months. They are allowed to

mate naturally at the age of 18-20 months (Gatenby, 1986b). The age at

puberty of ewes is 5-12 months and oestrous cycle is stimulated by the

presence of rams and nutrition (Carles, 1983).The first breeding age of

ewes is at 8-12 months, and the length of their reproductive life is

approximately 5 years (Devendra and Mcleroy, 1987). Thermal stress

reduces food intake and induces testicular degeneration in rams, which

results in the production of low quality semen (Robertshaw, 1985).

However, in ewes thermal stress suppresses conception rate and early

embryonic death may occur (Devendra and Mcleroy, 1987). In sheep,

high plane of nutrition favours early puberty, faster growth and better

libido and short reaction time in rams (Devendra and Mcleroy, 1987).

However, undernutrition during rearing periods delays puberty and sexual

maturity (Chemineau and Terqui, 1985). Sexual maturity may be delayed

even beyond one year of age on a low plane of nutrition or under

unfavourable climatic conditions (Grell, 1977).

1.3. Effects of nutritional factors The general nutritional requirements of sheep are

limited by the voluntary food intake which depends upon their reproductive and productive performance (Khalifa, 1971). However, the utilization of available nutrients is inversely related to the dry matter intake, the digestibility of food and level of dietary protein (Devendra, 1986). The fate of absorbed nutrients is influenced by the environmental conditions and the physiological responses of animals

(Weston, 1966). 1.3.1 Thermoregulation

The intake of food and thermoregulation are integrated and controlled by the hypothalamus, as the lateral hypothalamic area is designated as a feeding centre and the ventromedial one is a satiety centre. In sheep, food intake is regulated by a thermostatic mechanism and there is an inverse relationship between food intake and body temperature and the specific dynamic action (SDA) of food

(Blaxter et al., 1959). Seasonal changes influence food availability and consumption.The food intake, which influences the energy budget and thermoregulation, increases during winter as the maintenance requirements increase, and decreases in hot environment to avoid excess thermal loads (Young, 1981). Energy for maintenance of vital physiological processes is derived from the organic matter in food, while heat

increment of metabolism is associated with the level of feeding and the quality of food (Robertshaw, 1981). When the endogenous heat produced by food intake and metabolism sums with the exogenous heat of the environment, the heat load of the animal increases (Young and Degen, 1981). Consequently, metabolism increases to satisfy the requirements of more oxygen for the increased evaporative heat loss, and eventually the body temperature

rises (Robertshaw and Finch, 1976). In hot environment, high planes of feeding decrease the

heat tolerance of sheep (Blaxter and Boyne, 1982) and increase the rectal temperature and respiration rate (Webster and Johnson, 1968; Sano et al., 1995). However, low levels of feeding which decrease the metabolic heat production (Shmidt-Nielsen, 1995), reduce rectal

temperature and respiration rate (Naqvi and Rai, 1991). During food restriction, the energy requirements of mammals are obtained mainly from mobilization of proteins and fats (Panaretto, 1968). In the fasting state, the availability of energy depends upon utilization of body reserves to prevent tissue catabolism (Payne and Payne, 1987). These energy transformations usually interfere with body thermoregulation in animals (Nangia and Grag, 1988).

1.3.2 Blood metabolites

The changes in the nutritional status of sheep and seasonal changes in the thermal environment may influence the composition of blood.The heart rate, cardiac output and blood volume were higher in fed sheep compared to values obtained in fasting state (Burrin, 1989a). The arterial blood pressure was found to be polyphasic in fed sheep, while it was monophasic in fasting state with low blood volume due to reduction in the supply of blood constituents (Bianca,

1968). The formation of the cellular elements of blood

depends on the nutrients obtained from the animal feed. The plane of nutrition and level of dietary protein affect

erythrocyte count, PCV level and haemoglobin (Hb) concentration (Naqvi and Hooda, 1991). The PCV level and Hb concentration were higher with high plane of nutrition and high dietary protein content, while inanition decreased their levels in sheep (Payne and Payne, 1987). However, Nangia and Garg (1988) reported an increase in PCV level in starved sheep, which was attributed to dehydration as

water and food intake are positively correlated. In sheep the concentration of blood metabolites

represents an integrated index of the nutritional supply in relation to utilization of nutrients and it reflects the nutritional status of the animal. Feeding is the most effective stimulant of the normal diurnal pattern of blood metabolites and hormones in ruminants (Godden and Weekes, 1981); the levels of sugars and nitrogen increase shortly after feeding and fall gradually to the fasting level

(Sharma , 1973). The crude protein content of diet may influence the

nutritional status and the level of blood metabolites in sheep. High and medium levels of crude protein increase digestibility and efficiency of microbial degradation (Gill and Nagi, 1971; Mohan et al., 1987).Consequently, the concentrations of total plasma protein, albumin and urea increased with simultaneous increase in the rate of excretion of urea (Graham and Searl, 1966). However, the intake of low level of crude protein maintained the urea concentration at a constant level in the early stage, which subsequently decreased sharply (Farid, 1985). Although starvation results in excessive break down of body tissues, short-term fasting of Avivastra sheep in hot environment did not induce changes in the concentrations of total protein, albumin and urea (Naqvi and Hooda, 1991). These findings suggest that ruminants are capable of maintaining the level of blood urea during the dry season with scanty food by urea recycling

(Payne, 1990). In ruminants, propionate is the most important glucose

precursor obtained by microbial fermentation of

carbohydrates.When the glucose supply is limited, mobilization of body energy stores for glucose synthesis (and oxidation of spare glucose) will maintain a constant level of blood glucose (Brockman and Laarveld,1986). The utilization of glucose in sheep is efficient and its concentration exhibits a diurnal pattern (Sano et al., 1995). However, due to the continuous absorption of glucose and slow passage of food in the alimentary tract of sheep, it is not regarded as an indicator of the nutritional status (Khalifa, 1971). However, underfeeding in Suffolk wethers decreased blood glucose concentration (Moloney and Moore, 1994). During starvation, the decline in blood glucose level in ruminants is attributed to low concentration of propionic

acid (Naqvi and Hooda, 1991).

1.3.3 Semen characteristics The effects of nutritional stress on the gonads are more

pronounced in female than in male animals, which are encountered only in extreme conditions. A deficiency of energy and/or protein lowers male fertility by depressing semen production and characteristics (Setchell et al., 1965). Various studies in sheep have shown the deterioration of semen characteristics in response to undernutrition (Moule, 1970; Howland, 1975; Martin et al, 1987; Dun and Moss,

1992; Schillo, 1992; Martin and Walkden-Brown, 1995). Various neuro-peptides are involved in the central regulation of food intake(Igbal et al., 2003).Henry et al. (2000) suggested that neuropeptide Y (NPY) in the arcuate nucleus is a good example of the neural regulation for the reproductive axis in response to nutritional status of mammals . In feed restricted animals, NPY can elicit different effects on the secretion of luteinizing hormone (LH). High doses of NPY inhibit the productive axis in male sheep, and in feed restricted sheep NPY lowers LH secretion

(Henry et al., 2000). The nutrients required for sperm production are relatively small

compared to the requirements of growth (McDonald et al., 2002).

However, Hiore and Tomizuka (1965) found that loss of body mass in

male goats was associated with reduction in the output of spermatozoa,

while it had no influences in sheep (Tilton et al., 1964). However, Martin

and Walkden-Brown (1995) reported strong and direct relationships

between plane of nutrition, testicular mass and number of spermatozoa

available in the ejaculates of rams. Martin et al. (1980) observed an

increase in testicular size in association with high planes of nutrition of

sheep. However, prolonged severe undernutrition and poor supply of

energy and protein resulted in decrease in testicular size and production

of lower quality of semen (Knight, 1987).

In Merino rams, Oldham et al. (1978) indicated that an increase of 25% in testicular size resulted in 81% increase in production of spermatozoa.Setchell et al.(1965) noted that severe underfeeding of Merino rams for three months resulted in decreased diameter of seminiferous tubules and the proportion of the seminiferous tubules occupied by the seminiferous epithelium . In Merino rams, feeding for fifteen weeks at 75% or 50% of maintenance resulted in a progressive decline in volume, density and motility of the first ejaculate collected every week (Parker and Thwaites,

1972) . Martin and Walkden-Brown (1995) reported that in mature male sheep and goats, the absolute requirements for protein or energy for production of hormones and gametes is small and the endocrine function of testis is poorly related to nutrition. However, the authors reported hypothalamic pathways controlling gonadotrohpic releasing hormones (GnRH) which respond to nutritional changes. In mature Merino rams, changes in the production of spermatozoa in response to nutritional treatment resulted primarily from alterations in Sertoli cell function (Martin et al. 1994). The authors attributed this to changes in follicle stimulating hormone (FSH) secretion and testicular mass. On the other hand, the effects of nutrition on the activity of the interstitial

tissue were reflected in changes of rates of production of testosterone (Lincoln and Short, 1980). These changes are observed when loss of body and testicular mass is severe resulting in reduced testosterone production (Setchell et al., 1965; Gauthier and Coulaud, 1986; Jainudeen and Hafez,

2000). Rams kept for semen production need maintenance rations, and sub -maintenance level of feeding adversely affected their semen quality (Hafez, 1980). High and low levels of supplementary feeding of Merino rams resulted in marked differences; the high level was associated with superior semen characteristics, except for abnormal forms (Salamon, 1964). However, in hot environment, high levels of feeding resulted in deposition of fats, which may influence the fertility of rams (Hafez, 1980). During 23 weeks of starvation period of a bull, the levels of fructose and citric acid were the only variables of semen plasma constituents affected, as they decreased significantly indicating the rapid response of the accessory glands to nutritional deficiency

rather than testes (Mann and Walton, 1953). An adequate amount of dietary protein is essential for the synthesis of cytoplasmic protein from amino acids precursors which are performed by the spermatocytes (Nakamura et al, 1999; Price et al., 2000). The energy density of food rather than the protein content influences the secretion of gonadotrophins.In mature rams fed low energy rations for prolonged periods, libido and testosterone production were affected much earlier that semen characteristics (Martin et al., 1980). Glucose is needed in spermatogenesis to stimulate the incorporation of lysine into germinal cell protein in the testes, and most of the available glucose is utilized by Sertoli cells (Setchell and Hink, 1976). The semen characteristics are influenced by provision of sufficient amounts of vitamins and minerals in the diet. In mature rams, vitamin A and its precursors are essential to prevent testicular degeneration (Jainudeen and Hafez, 2000), while vitamin E deficiency may lead to degenerative

changes in the seminiferous tubules (Setchell, 1978). Iodine insufficiency reduced libido and addition of copper, cobalt, zinc and manganese improved semen quality in rams (Hafez, 1980). In mammals, calcium is implicated as a regulator for sperm motility (Turner, 2003). Kendall et al. (2000) indicated that in rams supplemented with selenium, zinc and cobalt, the semen had significant increases in motility, proportion of live sperms and proportion of intact

membranes. Garner and Hafez (2000) indicated that in bulls and rams the chemical components of seminal plasma are citric acid, ergothione, fructose, glycerolphosphorylcholine, sorbitol, protein and lipid. The authors also indicated that the chemical components of spermatozoa are nucleic acids, proteins and lipids. The changes in these components influence the semen pH. Milovanov (1962) indicated that semen pH is influenced by the proportion of the alkaline seminal plasma to the acidic epididymal secretions. Terrill (1968) noted that an alkaline reaction of semen was

associated with its poor quality. The effects of nutritional regime on reproductive performance of

laboratory animals have been investigated. In white-footed mice

(Peromyscus Leucopus), testicular regression was reported in response to

food restriction (Young et al., 2000).

1.4 Effects of thermal factors on male animals

In the tropics and subtropics, ambient temperature, humidity, and

solar radiation constitute important factors which influence the

microclimate and physiological responses of animals (El Nouty et al.,

1988). Ambient temperature is a convenient measure of the thermal

environment, as high ambient temperature induces heat stress. If the

effective ambient temperature rises beyond the thermoneutral zone (TNZ)

and exceeds the capacity of the thermoregulatory mechanism, the

increase in body temperature results in an impairment of the process of

spermatogenesis. However, in the temperate zone, the ambient

temperature and photoperiod are the main factors that trigger male

reproductive activity (Haynes and Howles, 1981).

1.4.1 Effects of seasonal changes in thermal environment

The circadian and circanual rhythm in animals are influenced by

changes in environmental conditions.The physiological adjustments allow

for maintenance of homeostasis (Da Silva and Minomo, 1995). Seasonal

changes in thermal environment induce changes in the energy budget and

neuro-endocrine responses of the animal (Payne, 1990; Pineda, 2004).

1.4.1.1 Thermoregulation

The seasonal and diurnal fluctuations in thermal environment may

induce marked changes in thermogenic responses of mammals. In

different seasons, the diurnal pattern adopted by sheep in rectal

temperature and respiration rate coincides with the diurnal changes in

environmental temperature (Menaker and Skin, 1968; Kaushish et al.,

1976; Lowe et al., 2001). The thermolability is controlled by attempts to

maintain homeothermy, a mechanism controlled by the thermoregulation

centre located in the hypothalamus (Hafez, 1968; Jessen and Clough,

1973) and the peripheral cutaneous receptors (Bianca, 1968). Sheep are

thermolabile animals; they are able to tolerate environmental temperature

changes (Terrill, 1968) through their elaborate countercurrent heat

exchange system in the upper respiratory tract (Backer and Hayward,

1968). When exposed to hot environment, sheep, being obligatory

homeotherms, react by increasing rectal temperature and often resort to

panting as the main avenue of evaporative heat dissipation and

maintenance of homeothermy when the ambient temperature is equal to

or greater than body temperature (Macfarlane, 1971 ; Degen, 1977; El

nouty et al., 1988; Patel and Dave, 1990). Also the adaptation of sheep to

hot environment is shown by a shorter steady rate of respiration and onset

of sweating (Hofmeyr et al., 1969).

Water metabolism might influence thermoregulation in mammals.

Sheep increase water intake and water turnover rate during summer in

order to facilitate evaporative heat loss, while in winter the water turnover

is reduced (Macfarlane, 1968).

The endocrine system contributes to thermoregulation. Trenkle

(1978) reported seasonal changes in adrenal and thyroid glands functions

which contribute to heat balance. The activities of both glands increase

during cold, thus contributing in maintenance of homeothermy by

increasing heat production. However, their activities decrease during hot

season, when it is beneficial to decrease endogenous heat production

(Salem et al., 1991). On the other hand, Weekes et al. (1983) observed

increases in the activities of catecholamines, adrenal corticoids and

thyroid hormones on prolonged exposure of sheep to low environmental

temperature so as to increase heat production and heat conservation.

1.4.1.2 Blood composition

Seasonal variations in thermal environment induce several

physiological changes which affect blood composition. The hot

environment increases the cardiac output and skin blood flow in

response to vasodilation which facilitates heat dissipation (Bianca, 1968;

Yeates et al., 1975a), while cold exposure decreases the cardiac output,

arterial blood pressure and skin blood flow due to vasoconstriction

(Hafez, 1968), and it increases hepatic blood flow (Thompson, 1977).

In sheep the circulating blood elements may exhibit seasonal

pattern. In adult sheep adapted to cold, a decrease in erythrocyte count

was observed by Young et al. (1989). Tropical breeds of sheep showed

low levels of packed cell volume (PCV) and haemoglobin concentration

(Hb) during summer (Sahni and Roy, 1972). However, Joshi et al. (1991)

reported a low PCV level in Patanwadi sheep during winter, which was

attributed to the low quality of pasture. In Desert sheep, the studies

performed by Hassan and Hoeller (1966) did not reveal seasonal changes

in PCV level and Hb concentration. However, Alsayed (1997) reported

higher values of these indices in winter compared to values obtained

during dry summer. Hassan and Hoeller (1966) and Alsayed (1997) reported higher total

leukocytes count and higher percentages of neutrophils and monocytes during wet

summer and winter in Desert sheep.

The neuro-humoral system has a seasonal pattern in controlling the

blood metabolites. Exposure of mammals to cold environments increases

the energy requirements for maintenance. Noradrenaline and glucagon

are involved in cold and heat acclimation through modification of lipid

metabolism. In cold acclimated sheep the secretion of noradrenaline and

the responsiveness to its metabolic action increase (Chaffee and Roberts,

1971), while in heat acclimated animals, the secretion of noradrenaline

and its systemic calorigenic action are reduced (Kuroshima et al., 1979).

The hot environment is associated with an increase in cortisol

level and decrease in thyroid secretions, which in turn reduce protein and

carbohydrate metabolism , while cold exposure increases their secretions

and functions (Souza et al., 2002). The concentrations of serum total

protein and albumin, which are used as indices for nutritional status,

increased during wet summer and decreased during winter in Desert

sheep (Alsayed, 1997). The seasonal changes in thermal environment may influence carbohydrate

metabolism and glucose kinetics. Chahal and Ratan (1982) reported an increase in blood glucose concentration during summer and acute cold exposure. The blood

glucose level increases due to liver gluconeogenesis under the control of catecholamines (Thompson, 1977).

1.4.1.3 Semen characteristics

The environment influences the reproductive activity in males

directly through the effects of elevated ambient temperature on the testes,

or indirectly through the photoperiodical changes which induce sequential

changes in the secretions of the gonadotrophins (Lincoln and Richardson,

1998).

In seasonal breeder males, photoperiod controls the reproductive

performance through the secretion of melatonin which stimulates neuro- -

hormonal control of testicular growth and function (Amir et

al.,1986;Colas et al., 1987; Stroud et al., 1992; McMillen et al., 1995;

Tayler and Field ,2004) via the hypothalamic-pituitary testicular axis

(Haynes and Howles, 1981).In temperate environments, under normal

seasonal fluctuations, rams exhibit a positive response to short-day length

( Hanif and William, 1991; Lincoln et al., 1998). However, in the tropics

rams do not show seasonal sexual activity (Amoroso, 1969; Dhillon et al.,

1979; Galil and Galil, 1982; Jainudeen and Hafez 2000; Abdalla, 2001).

The seasonal change in sexual activity is regulated by the

activities of endocrine glands. Gloria et al. (1994) reported that prolactin

modulates the intensity of expression of sexual behaviour in Dorset rams

which is season dependent. However, thyroid hormones are necessary for

the expression of neuro-endocrine mechanisms regulating

photorefractroriness or endogenous reproductive rhythm in males , and

seasonal inhibition of reproductive activity was greatly reduced when

rams were subjected to thyroidectomy (Parkinson and Follett, 1994,

1995). Thyroid hormones maintain a key role in regulating seasonal

reproduction in rams (Parkinson and Follett, 1994), and their deficiency

abolishes normal reproductive and endocrine function in rams (Dickson,

1996).

Souza et al. (2002) reported that in rams the thyroid hormones regulate hexosemonophosphatase activity, which

is an important source of energy for steroidogenesis, and a high level of thyroxine improves semen quality (Gerlach and Aurich, 2001). Tropical breed rams show low levels of thyroxine hormone in late winter and early autumn. However, high levels are shown in late autumn and spring, which is reflected in semen of high quality (Souza et al.,

2002). In Desert breed rams, Galil and Galil (1982 a,b)

reported higher semen quality in wet summer (rainy season) compared to dry summer and winter values. Ibrahim (1997) reported marked seasonal variations in the sexual activity of Egyptian rams and their Chios crosses; higher semen quality was obtained in winter compared with values obtained in summer. Awassi and Border Leicester rams showed high values of seminal traits during autumn and lower values

were reported during winter (Amir and Volcani, 1965b). Seasonal pattern in semen quality was also observed in tropical breed bucks (Degen, 1977; Ali and Mustafa, 1986), and in bulls summer adversely affected semen quality

(Choudhury and Sadhu, 1978). Little research has been conducted on the effects of cold environment on spermatogenesis in farm animals. In some laboratory animals, cooling the testis or scrotum below the freezing point resulted in decapitated sperms and inhibition of spermatogenesis and endocrine function

(Hafez, 1968). 1.4.2 Effects of exposure to solar radiation

Solar radiation constitutes one of the important environmental factors; it includes infrared, ultraviolet and visible light, and it changes throughout the day (Gates, 1968). All vital processes in mammals depend upon solar heat and they are directly influenced by its variations

(Robertshaw, 1985). The thermal consequences of solar heat for animals

depend upon a complex array of factors including the other climatic variables, the coat characteristics, the orientation of the body to the direct solar beam which animals intercept,

and the reflectance of the coat (Clapperton et al., 1965; Cena and Monteith, 1975; Walsbery et al., 1978; Robertshaw,

1981). 1.4.2.1 Thermoregulation

Excess solar heat may alter the general physiological responses and it enhances animals to adjust their body temperature (Das et al., 1999). In mammals, the regulation of body temperature under conditions of high thermal load is a complex problem involving physiological and

behavioural adaptation. The magnitude of heat and prolonged exposure of

animals to solar heat load induce heat stress (Macfarlane, 1968). Heat loss is enhanced by thermal gradient between the body and air (Ingram et al., 1963; Degen, 1977), and the heat absorbed during the day is dissipated by sensible

channels during the night (Robertshaw, 1985). Direct exposure of sheep to solar radiation stimulates

peripheral thermoreceptors (Mitchell, 1977) and increases rectal temperature and respirtation rate (Diwivedi, 1976; Patel and Dave, 1990). In heat stressed sheep, respiration rate varies from 20 to 50 breaths/min up to 300 breaths/min (Terrill, 1968). On exposure of Desert sheep to direct solar heat, the respiration rate reported varied from 88 breaths/min in the morning to 159 breaths/min in the afternoon (Abdelatif and Ahmed, 1992), which coincides with the diurnal fluctuations in ambient temperature and solar radiation. On exposure of Desert sheep to solar radiation under summer conditions, the rectal temperature

in the afternoon increased to 41°C (Abdelatif, 1978). 1.4.2.2 Blood composition

Thermal stress induced by the high intensity of solar radiation could modify blood composition via the neuro-humoral responses. Thermally stressed sheep revealed increases in cardiac output, blood volume and increases in blood flow to the skin, which is associated with vasodilatation (Hales, 1973 a, b). Acute heat exposure of sheep stimulated an increase in cortisol secretion which

tended to decrease gradually (Christeson and Johnson, 1972; Buragohain et al., 1986).Furthermore, prolonged exposure to thermal stress was associated with reduction in the secretion of glucocorticoids (Bareham, 1975), decrease in

food intake and metabolic rate (Singh et al., 1982) . In Barki sheep, an increase in water intake was

reported during summer heat stress associated with haemodilution and lowering of PCV (Hassanain et al., 1996); also low PCV level was reported by Abdelatif (1978) in Desert sheep when experimentally subjected to heat exposure. However, exposure of Desert rams to direct solar heat did not influence the PCV level (Abdelatif and Ahmed, 1992). The increased adrenal activity under thermal stress interferes with immune responses (Joshi et al., 1979); the total leukocyte count was reported to decrease in sheep on prolonged exposure to heat due to adaptation (Gutierlez et

al., 1971). Ahmed (1989) reported an increase in the

concentration of plasma total protein of heat stressed Desert rams, while urea concentration decreased. Guerrini et al. (1982) reported an increase in total plasma protein concentration in Lettelle wethers exposed to solar radiation, which was attributed to decrease in urinary nitrogen However, when Desert sheep were experimentally exposed to acute heat stress, lower values of plasma total protein and albumin were reported, while the urea concentration increased; chronic heat exposure was associated with a

decrease in their levels (Abdelatif, 1978). Exposure to solar radiation may influence the utilization of carbohydrates .Solar heat load increased blood glucose concentration in Barki sheep (Hassanain et al., 1996) and Desert rams (Abdelatif and Ahmed, 1992). Singh et al. (1982) reported a low blood glucose level when Rambouillet and Chokla cross sheep were subjected to summer heat stress. Khogali et al. (1983), using Merino sheep as an experimental model in heat stroke studies, reported an increase in blood glucose concentration in response to controlled thermal

environment of 42-45°C and relative humidity of 40-50% for 120 min.

1.4.2.3 Semen characteristics High thermal load induces physiological stress which

promotes an unfavourable endocrine balance such as general hypofunction of the anterior pituitary. This results in insufficient secretion of gonadotrophins, inadequate secretion of male reproductive hormones and consequently reproductive failure (Hafez, 1968, Lincoln and Richadson,

1998). Solar radiation modifies the reproductive activity in

the male through elevation of ambient temperature and effects of hyperthermia on testicular tissue. However, body temperature responses to heat stress which contribute to testicular cooling, are well characterized in rams (Kastelic et al., 1996). Mount (1979) reported that polypnoea could be evoked by heating the scrotum of Merino rams. In hot environments, thermal stress induced testicular degeneration (Blom, 1969; Kastelic et al., 1996). Extremely high temperatures have adverse effects on spermatogenesis, which in turn contribute to impaired fertility (Ax et al.,

1987). Testicular thermoregulation mechanism in mammals

was reported to be favoured by large scrotal sweat glands and scrotal insulation (Kastelic e.al., 2000). Wierzbowski and Kareta (1993) reported disturbance in testicular thermoregulation in Merino and Romney March rams of wooly scrota under thermal load. However, poorly protected scrota may be receptive to thermal load which adversely affected testicular tissues and consequently semen quality

(Mieusset et al., 1992; Mieusset and Bujan, 1995). Generally, in experimentally induced hyperthermia,

rams produced semen of low quality (Howarth, 1969; Rathore, 1970; Matos and Thomas, 1992). In Desert rams exposed to continuous heating at 43.0°C and 48% RH for different periods, semen samples of abnormal characteristics were obtained (Galil and Galil, 1982 a

,b).Regular collection of semen samples from scrotum insulated in hot bags for 96 hrs in Montadale and Taxel cross rams showed an increased percentage of abnormal

sperms (Ibrahim et al., 2001). 1.4.3 Effects of thermal environment and shearing

The body external insulation consists of coat and air insulation. In all thermal environments, the role of the coat in mammals is to provide protection against penetration of solar radiation and consequently alleviate heat stress, and to reduce heat loss during exposure to cold weather (Folk, 1973). In the tropics, most mammals are of hairy coat (Macfarlane, 1968), and Desert sheep are exclusively haired

(Mcleroy, 1962 c). In the tropics and subtropics, the physical

characteristics of coat are modified in response to seasonal changes in thermal environment. The growth of body coat increases during winter and decreases during summer (Grell, 1977). The colour of the pelage controls the degree of radiant heat reflection, as the white color reflects a higher proportion of radiant heat and the black colour absorbs it (Cena, 1973). At all wave lengths, the reflectivity of a naturally greasy fleece is substantially less than the value for a clean sample of the same origin. Macfarlane (1968) found that the reflectivity of the coat of Merino sheep doubled to 0.7 Kcl/m2/hr when the white cut ends of fibres were exposed after shearing. In temperate breeds of sheep, Clapperton et al. (1965) reported an increase in coat reflectivity from

about 0.25 to 0.5 Kcl/m2/hr after shearing. 1.4.3.1 Thermoregulation

The coat insulation represents thermal resistance to the flow of heat from the skin to the surface of the hair coat, and its presence helped reduce the rise in both rectal temperature and respiratory rate when sheep were exposed to high ambient temperature (Lee, 1950). On exposure of Southdown ewes to infrared irradiation, heavy fleece interfered with the efficiency of evaporative heat loss, while

shearing rendered them more heat tolerant (Webster and Johnson, 1968).

Shearing of sheep increases the reflectivity of fibres (Cena, 1973). In the tropics, shearing of sheep is supposed to alleviate thermal stress and offer a number of husbandry advantages. Shearing of Desert sheep facilitates heat dissipation when environmental temperature is below body temperature (Ahmed, 1989). Exposure of shorn sheep to direct solar heat increased heat gain and body temperature and induced changes in energy balance and fluid dynamics (Macfarlane et al., 1966; Kaushish et al., 1976), with consequent increases in water intake, water turnover rate and extracellular fluids. However, winter shearing markedly influenced the heat balance of sheep (Turnpenny et al., 2000), as body core temperature tended to be lower, particularly in the morning due to enhancement of heat loss

via the skin (Eyal, 1963b; Kaushish et al., 1976). In shorn sheep, the evaporative heat loss by sweating

plays an important role in thermoregulation (Younis et al., 1977; Mittal and Ghosh, 1979), and it complements evaporative loss by panting which assumes a major role, particularly in hot environment (Mclean, 1973). Panting is independent of the coat covering of the animals, as the sheep coat insulates against heat without interfering with the cooling mechanism. In Desert rams, shearing was not associated with a significant reduction in respiration rate

(Ahmed and Abdelatif, 1992). 1.4.3.2 Blood composition

Shearing of sheep may induce physiological and metabolic responses which influence blood volume and

composition. Heat exchange alterations induced by shearing

increased skin blood flow related to vasodilatation and reduction in vasomotor tone (Bianca, 1968).Summer shearing of Merino wethers increased plasma volume (Macfarlane et al., 1966). However, Kaushish et al. (1976) reported an increase in PCV level in autumn in shorn sheep

and a low level of PCV was observed in animals shorn during summer; these findings were attributed to changes in

feed intake. Shearing influences the availability of nutrients for

blood constituents through its effects on feed and water intake, as they are modulated by changes in environmental temperature. Low ambient temperature increased the energy requirements of sheep (Cheeke, 2005b), which was associated with decreased digestibility. However, at high ambient temperature, decreased food intake was associated with the demand for evaporative heat loss and high water turnover rate (Abdelatif and Ahmed, 1992). These changes are usually associated with marked disturbances in the

metabolism of energy and water (Macfarlane, 1968). Shearing of Desert rams under dry summer conditions

increased the total amount of nitrogen ingested and excreted , while the amount of nitrogen retained decreased (Ahmed and Abdelatif, 1992).The authors also reported that shearing was associated with an increase in plasma urea level and a decrease in the level of free fatty acids . In Merino wethers shorn during summer, Macfarlane et al. (1966) reported a decrease in the level of plasma protein. Sano et al. (1995) experimentally subjected shorn Suffolk rams to a cold environment and reported increases in non-protein oxidation and the concentrations of glucose and free

fatty acids. 1.4.3.3 Semen characteristics

In hot environment, heavy wool with high body insulation might be detrimental to the fertility of rams. Shearing might induce lowering of body and/or testicular temperature during hot weather than unshorn rams, with

improvement in fertility (Waites and Voglmayr, 1963). Pijoan and Williams (1984) reported that shearing of rams before the hot

season reduced the adverse effects of heat stress on semen quality. This response is

related to enhancement of cutaneous evaporation and scrotal sweating which provide

an effective thermoregulation mechanism and increase heat tolerance of rams

(Alexander, 1973). However, Hullet et al. (1956) observed a high semen quality and

fertilizing rate in shorn Hampshire, Shropshire Oxford and Corriedale rams during

winter compared to hot season. In unshorn Chokla rams with closely clipped

scrotum, the relative sweating response, compared to the other body regions, was

higher due to the large number of scrotal sweat glands which resulted in lowered body

temperature (Rai et al., 1979).

1.5 Effects of frequency of ejaculation

There is an increasing interest in assessment of the potential for

sperm production in domestic mammals as it may influence the

reproductive performance and breeding capacity (Honmode and Tiwari,

1974). 1.5.1 Frequent ejaculation of semen and assessment of male reproductive

capacity

Removal of large numbers of sperms by exhaustion test is one of

the most adequate methods for estimating sperm production and

reproductive capacity of males (Salamon, 1964 b). Furthermore,

successive ejaculation facilitates evaluation of ejaculatory responses and

perhaps provides evidence of incomplete ejaculation (Pickett and Voss,

1998). Faster ejaculation indicates the superior mating ability of the male,

which is important in rams when female-to-male ratio is relatively high

(Price et al., 1996). In rams, more frequent ejaculation, probably to the

point of exhaustion and refusal of service is necessary for the

measurement of ejaculation capacity and semen characteristics (Salamon,

1962).

Exhaustion test reflects the degree to which males may be used in

intensive breeding programmes and also helps in detecting the effects of

nutritional and seasonal factors (Foote, 1978). Salamon (1964 a) noted

that in Merino rams given high level of supplementary feeding for 6

weeks and subjected to intensive semen collection every 15 weeks for 18

months using artificial vagina, the semen quality was higher compared to

values obtained for the respective low level of feeding group. However,

the author reported low values of sperm motility and sperm cell

concentration and high percent of morphologically abnormal sperm in

high level of feeding group, particularly during mid-summer. On the

other hand, frequent ejaculation of Merino rams, 8 times a day for 8 hours

weekly for 7 weeks accompanied with exposure to 43°C room

temperature, lowered the ejaculate volume and diminished sexual activity

and its effect persisted 2-3 weeks after treatment (Lindsay, 1969).

In seasonal breeder rams, hypoprolactinaemia is associated with the

short photoperiodism and consequently the expression of sexual

behaviour and the frequency of ejaculation (Gloria et al., 1994).

1.5.2 Effects of frequent ejaculation on semen characteristics

Rams can serve several times a day when newly introduced to

ewes; they maintain a higher frequency of mating (2-3 times in few

minutes), but they tend to mate at a rate of once every 1-5 hours when

continuously kept with ewes on heat (Hullet, 1966).

Frequent ejaculation affects the sexual activity and semen

characteristics in different breeds of rams (Danove et al., 1967; Foote and

Trimberger, 1969; Jennings and McWeeney, 1976). However, there are

little or no problems in maintaining a continuous sexual drive, and their

semen was not depleted immediately due to their small ejaculate and

large epididymal reserve (Foote and Trimberger, 1969). A period of 5-6

days is required for passage of the spermatozoa through the epididymis of

the frequently ejaculated rams (Howarth, 1969).

In Merino rams, collection of semen successively, 11 ejaculates per

day for 5 consecutive days using artificial vagina, significantly reduced

ejaculate volume and sperm cell concentration. However, mass motility

and abnormal sperm percent were not affected (Salamon, 1962). On the

other hand, 13 ejaculates per day for 10 consecutive days decreased

ejaculate volume, sperm concentration and the concentration of fructose

and citric acid, while it increased the reaction time (Salamon, 1964 b). In

Najdi rams, repeated electro-ejaculation of semen samples, 2 to 6 times a

day at hourly intervals decreased the ejaculate volume, mass and

individual motility, sperm concentration and live sperm percent, while the

semen pH increased (Galil et al., 1984). Galil and Galil (1982 a,b )

reported lower values of ejaculate volume, mass and individual motility,

sperm concentration and live sperm percent when semen samples were

collected frequently every 30 minutes for 10 consecutive days from

Desert rams. However, abnormal sperm percent and the semen pH

increased and fructose concentration was not affected by increasing

ejaculation frequency. High ejaculation frequency induced specific

biochemical changes in the spermatozoa similar to apoptosis in somatic

cells (Strezezek et al., 1995). Kaya et al. (2002) reported lower ejaculate

volume, sperm concentration and progressive motility when Konya

Merino rams were subjected to 12 days of frequent ejaculation consisting

of 4 consecutive phases, each phase continued for 3 consecutive days.

The changes observed were elevated concentrations of Na and K ions in

seminal plasma.The authors also reported spermatozoal membrane

damage which was associated with high abnormal sperms percent in

addition to inadequate epididymal maturation.

Studies on male goats also indicated the effect of frequent

ejaculation on seminal traits. Ritar et al. (1992) reported lower ejaculate

volume and sperm concentration when Angora bucks were subjected to

successive collection of semen. In West African dwarf bucks,

an increase in frequency of ejaculation significantly decreased ejaculate

volume, sperm concentration and progressive motility, while it

insignificantly increased abnormal sperm percent and semen pH; live

sperm percent was not affected by the treatment (Oyeyemi et al., 2001).

Various studies performed on bulls also indicated that frequent

ejaculation was associated with marked changes in semen characteristics.

Amann and Almiquist (1976) reported that collection of semen six times

a week increased sperms number and motility in Holstein bulls compared

to values obtained following semen collection once a week. However,

using electro-ejaculation method for collection of semen, six successive

collections at 15 minutes intervals from Hereford, Ayershire and

Shorthorn breeds of bulls had no effect on sperm abnormalities (Ghallab

et al., 1981).

Strezezek et al. (1995) found no marked increase in dead sperms

percent in boars in response to frequent ejaculation; however, frequent

ejaculation resulted in mid-piece damage and acrosomal disintegration.

In boars, successive collection of semen reduced resistance for

capacitation in acrosomal membrane of sperm cells due to insufficient

epididymal maturation (Schilling and Vergus, 1987).

Collection of semen once or twice daily did not affect sperm output

in stallion. However, in stallions of sufficient sex drive, several

ejaculations per day reduced their fertility because of insufficient

numbers of sperms. On the other hand, the extragonadal sperm reserve

(EGR) in the epididymal tail was depleted by successive collection of

semen (Pickett and Voss, 1998).

1.6 Objectives The process of reproduction in mammals requires

adequate nutrition and suitable environmental conditions. The basis of adequate nutrition includes availability and continuous ingestion of all nutritionally and biologically valuable substances required by the animal ( McDonald et al., 2002). However, animals have to adapt to extreme

thermal conditions in order to maintain their vital physiological activities.

In the tropics, inadequate forages in dry summer conditions and exposure to extreme thermal environment may influence the general physiological responses of sheep; the cumulative effects of theses factors retard their reproductive performance. Under natural field conditions, Desert rams have to combat the harsh environmental conditions and perform mating throughout the day. Previous studies were carried out to investigate the effects of water and food restriction, exposure to solar radiation and food composition and shearing and exercise on the physiological responses of Desert rams (Ahmed, 1989). The effects of season, exposure to heat stress and exhaustion test on physical and biochemical semen characteristics were also evaluated (Galil and Galil, 1982 a,b). Many studies were performed to assess the effects of season and food intake (Weston, 1966; Godden, and Weekes, 1981; Cheeke, 2005b), and the relationship between level of feeding and environmental temperature on the physiological responses of sheep (Young and Degen, 1981; Naqvi and Rai, 1991; Naqvi and Hooda, 1991). However, few studies have dealt with the effects of nutritional factors on semen characteristics (Hafez, 1980; Lincoln and Short, 1980; Martin and Walkden-Brown, 1995; Jainudeen and Hafez, 2000). This project was designed to investigate the effects of essential nutritional and environmental treatments on the physiological responses and semen characteristics in Desert rams. The studies were

conducted to evaluate the following relationships: 1. The effects of season and level of feeding lucerne hay

on thermoregulation, blood metabolites and semen

characteristics.

2. The effects of exposure to solar radiation on

thermoregulation, blood composition and semen

characteristics and the responses to frequent

ejaculation.

3. The effects of season and the responses to shearing on

thermoregulation, blood composition and semen

characteristics and the responses to fasting.

CHAPTER TWO

MATERIALS AND METHODS

2.1 Experimental animals

A total number of 10 adult entire, sexually mature and apparently healthy Hamari Desert rams (Ovis aries)

were used in the studies. The rams were selected following proper clinical screening of external genitalia and semen

evaluation. The animals were 2-3 years old, with initial mean body weights of 39.0-40.5 kg. The rams bore the

characteristic features of Sudanese Desert sheep. They were deep bodied and haired and had long tapering tails. The coat

hair which was predominantly brown was thick and coarse. The rams were identified individually using ear tags.

Although all the rams were apparently healthy, they were dewormed by an anthelmintic (lvermectin 1ml/50 kg –

ANOUP Company), and were given prophylactic doses of antimicrobial therapy (Ancomycin 200 L.A./5ml/50kg-

ANOUP Company). 2.2 Housing and management

Different systems of housing and management were used in the experiments. In experiment 1, in which the effects of level of feeding lucerne hay were studied, the

animals were accommodated individually in separate pens. They were fed lucerne hay (Medicago sativa) prepared by

drying fresh materials under the sun, and then chopped and mixed thoroughly before feeding. Lucerne hay was offered

ad libitum for rams exposed to direct solar radiation in experiment 2. Free grazing was allowed in experiment 3.

The animals were put to pasture and allowed to graze daily on sorghum residues (Sorghum vulgare) and grasses (Cydom

dacylon) and lucerne. The chemical composition of feeds is given in Table 1.

Table 1. The chemical composition of the feeds (%) on

dry matter basis .

Lucerne

(Medicago sativa) Abu Sabien

(Sorghum vulgare) Dry matter

Metabolizable energy(MJ/kg)

Crude fibre (%)

23 8.48

30.00

10 8.96

38.6

Crude protein (%) 17.5 6.85 Ether extract (%) 0.99 3.00

Nitrogen free extract (%) 40.27 40.00 Ash (%) 11.57 8.52

2.3 Rectal temperature (Tr)

The rectal temperature (Tr) of the rams was measured according to

the experimental protocols, twice daily or twice weekly, in the morning

(7:00 a.m.) and in the afternoon (2:00 p.m.). The Tr was measured to

the nearest ± 0.1ºC using certified mercury -in- glass clinical thermometer

(Wilson-Supreme,Japan), inserted approximately 8 cm into the rectum for

2 min. before the reading was obtained.

2.4 Respiration rate (RR)

The respiration rate (RR) of the rams was measured visually by

counting the flank movements with the aid of stop-watch. The values

were taken for one minute of regular breathing with the animal standing

quietly.

2.5 Body weight (BW)

During the experimental period, the rams were weighed to the

nearest ± 0.1 kg using a spring balance (Salter No. 235-Trade No. 2892 –

England).

2.6 Scrotal circumference (SC) The scrotal circumference was measured according to the method

described by Boundy (1992). Both testicles were pressed downwards into

the scrotal sac, and then using a tape located around the widest part of the

testis , the circumference was measured to the nearest ± 0.1cm.

2.7 Collection of samples

2.7.1 Blood samples

Blood was collected from the rams under aseptic conditions from the jugular vein using plastic disposable

syringes.A sample of 5ml was collected and immediately 1 ml was transferred to a test tube with anti-coagulant (Tri-

sodium ethylene-diamine-tetra-acetate, EDTA) for the measurements of the erythrocytic and leukocytic indices. 2

ml of blood was also transferred to a test tube with anticoagulants, EDTA and sodium fluoride; these samples of

blood were centrifuged for extraction of plasma samples for glucose determination. Sodium fluoride was added to inhibit the enzymatic reactions that influence glucose

concentration (Kelly, 1984). The rest of the blood sample was left at room temperature for 2-3 hrs and then

centrifuged for extraction of serum samples. Haemolysis free serum samples were stored at -20ºC for subsequent

measurements of the concentrations of metabolites. 2.7.2 Semen samples

Semen samples were collected by electro-ejaculation according to the method described by Blackshaw (1954)

using the Raukura ram design of probe (Mark IV OLVET, New Zealand). The rams were controlled lying on the right

side, the rectum was evacuated of faeces and then the electro-ejaculator was lubricated with vaseline and inserted

8 cm into the rectum. An electric charge of 12 volts was applied for 5 seconds, followed by a pause of 8 seconds. This

was repeated 5 times. Semen ejaculated during the pauses was received in graduated tubes. The samples were

examined immediately after collection according to the standard techniques and methods.

2.8 Analysis of samples 2.8.1 Blood samples

The analyses of blood samples were carried out according to the standard methods described in Schalm’s

Veterinary Haematology (Jain, 1986). 2.8.1.1 Packed cell volume (PCV)

The packed column of erythrocytes (PCV), expressed as a percentage of whole blood, was determined in plain

capillary tubes using a microhaematocrit centrifuge (Hawksley, London), operated for 5 min. This method is

more accurate, reproducible and the amount of blood used is minimal.

2.8.1.2 Leukocytic indices 2.8.1.2.1 Total leukocyte count (TLC)

The TLC was performed microscopically under low power (x10 objective) using the improved Neubauer

haemocytometer. 2.8.1.2.2 Differential leukocyte count (DLC)

Blood films were prepared in duplicate. The films were fixed in methanol and stained with Giemsa stain. The leukocytes were differentiated and counted using oil

immersion lens (x100 objective) of light field microscope. The values are reported as a percentage from the counting

of 100 leukocytes from each slide. 2.8.2 Serum samples

The serum concentrations of total protein, albumin and urea were determined using the spectrophotometer

(JENWAY-6150 .U.V.USA). 2.8.2.1 Serum total protein

Serum total protein concentration was determined by the Biuret reagent method described by King and Wooton

(1965). In this method, the peptide bonds of plasma proteins diluted with isotonic solution of sodium chloride react with alkaline copper sulphate to give a violet colour. The optical

densities were measured at a wave length of 540 nm. 2.8.2.2 Serum albumin

Serum albumin concentration was determined by the colorimeteric method of Bartholomew and Delany (1966), using bromo-cresol green (BCG) reagent. BCG has been

used at pH 3.8-5.0 depending upon the dye binding reaction. Brophenol-blue colour changes from yellow to blue on

adding alkalis. The blue colour indicates the divalent anion and the yellow colour is formed from undissociated phenol

group which forms the blue complex with albumin. The optical densities were measured at a wave length of 637nm.

2.8.2.3 Serum urea Serum urea concentration was determined by the

colorimetric method of Evans (1968) using diacetyl monoxime (DAM) and thiosemicarbazide (TSC) reagents.

DAM when treated with urea decomposes to give hydroxylamine and diacetyl which condenses with urea.

TSC, ferric ions and strong acids are added to catalyse the reaction forming a complex colour. The optical densities

were measured at a wave length of 520 nm. .2.9 Plasma glucose

Plasma glucose concentration was determined by the colorimetric method using a commercial kit (Aromex-

Amman, Jordon). This method was adopted by Barham and Trinder (1972). The enzymatic oxidation occurs in the

presence of glucose oxidase. The hydrogen peroxide formed reacts with phenol and 4-amino-phenazone to produce a red

violet dye as an indicator. The optical densities were measured at a wave lengeth of 540nm.

Glucose Glucose + O2 + H2O ─────→ Gluconic acid + H2O

Oxidase

2.10 Semen samples

Semen samples were analyzed according to the methods described

by Boundy (1992, 1993) and Ax et al. (2000).

2.10.1 Appearance

Immediately after collection of semen samples, the colour and

consistency were determined visually for abnormal colour and whether

the sample is thick or watery. Semen samples of rams are usually of

creamy or milky colour; brown colour indicates the presence of blood,

while greenish colour indicates the presence of pus due to infection of the

genital tract.

2.10.2 Ejaculate volume

The volume of semen sample was determined after collection using

graduated tubes. The graduation ranged from 0.5 to 10 ml. The volume

of the sample was measured to the nearest ± 0.1 ml.

2.10.3 Sperm mass motility (MM)

Mass motility (wave motion) estimation was carried out

immediately after the collection of semen sample.Using Pastuer pipette a

drop of undiluted semen was delivered on an uncovered clean warmed

slide and examined under low power (x10 objective) using a binocular

light microscope. According to the wave motion of swirling bands of

spermatozoa, the scores ranging from 0 (indicating immotile

spermatozoa) to 5 (indicating high motility) were recorded.

2.10.4 Sperm individual motility (IM)

Estimations of individual motility were carried out by diluting a

drop of semen by 4 drops of normal saline (0.9% NaCl). A drop of the

diluted semen was situated on a warm slide covered by a cover slip and

examined microscopically (x45 objective). Estimates of progressively

motile cells were made.

2.10.5 Sperm cell concentration

For the determination of the concentration of spermatozoa in

semen samples, the red cell counting apparatus was used. Semen sample

was drawn by the pipette until the mark 0.5, and then formol-saline was

drawn until the mark 101. After gentle shaking and waiting for 5 min, the

first 4 drops were discarded, and then a drop was introduced under the

cover glass of the heamocytometer. After settlement of the spermatozoa,

they were counted microscopically (x45 objective), adopting the method

used for counting red cells. The total number of spermatozoa was

multiplied by 109 to obtain the number of sperms in one millilitre of

normal semen sample.

2.10.6 Incidence of live sperms

Immediately after the estimation of the sperm motility, a drop of

semen was mixed on a warm slide with 4 drops of warm Nigrosin-Eosin

stain (Hancock, 1951), and a thin smear was prepared. The dead sperm

head takes up the eosin stain, whereas the live sperm does not. The

difference was assessed against the dark background imparted by the

Nigrosin stain and the percentage count was made of the live sperms

under oil immersion lens (x100 objective).

2.10.7 Incidence of abnormal sperms

The slide used to determine live sperm percent was used to

determine morphologically abnormal sperm. Abnormalities in

spermatozoal morphology are divided into primary and secondary

abnormalities. Primary abnormalities are abnormal size and form of the

head, abaxial tails , double heads, double tail, dag tail (tail tightly coiled

around the midpiece) . which develop during spermatogenesis. Secondary

abnormalities are usually associated with distal droplets, bent and coiled

tails which develop during epididymal transit. All these abnormalities

were calculated as percentage from 200 randomly examined spermatozoa

under oil immersion lens (x100 objective).

2.10.8 Hydrogen ion concentration (pH)

The indicator papers (E. Merk Company, Darmstadt, Germany)

were used to determine the pH of semen samples. The papers of pH

range of 5.2 to 8.0 were used by applying a drop of semen sample and the

colour developed was matched with the standard colour.

2.11 Climatic measurements

The daily maximum, minimum and mean ambient temperature (Ta)

and the relative humidity (RH) readings were obtained from Shambat

Meteorological Centre located about 500 meters or 1 Km from the

experimental site. The data were utilized in computation of the mean

values of temperature and humidity during the experimental periods.

2.12. General experimental plan

The general experimental plan is outlined in Table 2.Three

experiments were designed and conducted to study the effects of seasonal

changes in thermal environment and level of feeding lucerne hay, the

effects exposure to solar radiation and exhaustion test, and the effects of

seasonal changes in thermal environment and shearing and exhaustion

test on thermoregulation, blood composition and semen characteristics of

Sudanese Desert rams. The details of the experimental procedure for

each experiment are presented in the specific chapter.

In each experiment, an adaptation period of 14 days was allowed

before the commencement of proper measurements. During this period,

the animals became used to the experimental conditions, handling and

collection of blood and semen samples.

In experiment 1, during summer and winter, the animals were divided into 3 groups of 3 rams each and kept

individually in shaded pens. They were fed high, medium and low levels of chopped leucerne hay and had free access

to water. In each season, Tr and RR were measured daily and blood and semen samples were collected weekly for 3

months. In experiment 2, the animals were divided into 2 groups of 4 rams each (A and

B). Group A animals were shaded while group B animals were exposed to solar

radiation. Chopped lucerne hay and water were offered ad libitum. Measurements of

rectal temperature (Tr) and respiration rate (RR)

Table 2. General experimental plan

Exp.No. Treatment Season

No. of animals

used

ExperimetalPeriod (week)

Measurements

1 Effects of Feeding level of

Summer and

winter

9 12 • Tr,RR

• Blood parameters

lucerne hay • Semen

characteristics

• Scrotal

circumference

2

Effects of exposure to

solar radiation

and exhaustion

test

Wet summer

8 5 • Tr,RR


• Semen

characteristics

• Scrotal

circumference

3 Effects of

shearing and fasting

Summer and

winter

8 5 • Tr,RR


• Semen

characteristics

• Scrotal

circumference

were recorded daily. Blood and semen samples were collected weekly for

three weeks. During the fourth week, the exhaustion test of rams was

performed for 3 successive days by frequent ejaculation.

In experiment 3, during summer and winter, the animals were

divided into 2 groups of 4 rams each (A and B). Group A animals had

intact pelage and group B animals were shorn. All animals were allowed

to graze the available pasture at the University Farm in Shambat with free

access to water.During the experimental period, weekly measurements of

Tr and RR were performed. Blood and semen samples were collected

weekly for 4 weeks. During the fifth week the animals were subjected to

fasting , blood samples were collected before and after fasting.

2.13. Statistical analysis

The statistical analysis was performed using the Statistical

Analysis System (SAS, 1997). The analysis of variance (ANOVA) test

was used to evaluate the effect of season and level of feeding lucerne hay

,the effects of exposure to solar radiation and exposure to solar radiation

and exhaustion test and the effects of season, shearing and fasting on

thermoregulation, blood composition and semen characteristics of Desert

rams.

CHAPTER THREE

EFFECTS OF LEVEL OF FEEDING LUCERNE HAY

AND SEASONAL CHANGES IN THERMAL ENVIRONMENT

ON THERMOREGULATION, BLOOD METABOLITES

AND SEMEN CHARACTERISTICS

3.1 Introduction

In the tropics, seasonal changes in climatic conditions and forage quality and

quantity constitute constraints to sheep production (Rowe, 1989). Although sheep are

allowed to graze freely, sufficient nutrient requirements for maintenance and

production may not be available (Devendra and Mcleroy, 1987). The energy density

of food is necessary for maintenance of the body functions (McDonald et al. 2002),

and the productive and reproductive state of sheep may influence the energy

requirements (Antounovic et al., 2002). The food intake and efficiency of energy

utilization are altered by effective ambient temperature (Gillespie, 1998). The plane of

nutrition influences the energy budget and the thermoregulatory capacity of sheep and

other species of mammals (Robertshaw, 1985).

The spermatogenic cycle in rams is 10 days (Stabenfeldt and Edqvist, 1993)

and the process of spermatogenesis which involves mitotic proliferation, meiotic

division and differentiation of the haploid spermatids and maturation of spermatids

into spermatozoa is about 40 days (Bilaspuri and Guraya,1986). The process of

spermatogenesis is sensitive to physiological changes brought about by thermal and

nutritional stresses (Evans and Maxwell, 1987). Various studies have demonstrated

the deleterious effects of high thermal load on spermatogenesis (i.e. testicular

degeneration and abnormal sperms) under temperate (Gordon, 1997; Jainudeen et al.,

2000) and tropical environmental conditions (Chemineau et al., 1991; Abdalla, 2001).

These effects may have serious implications regarding fertility of rams and

reproductive activity of sheep during hot dry summer conditions. Early investigations

assessed the sexual function of inadequately fed males from semen samples and from

histological studies of the testes (Moule, 1963; Setchell et al., 1965). A high level of

feeding was shown to improve semen quality and increase scrotal circumference

(Sutama and Edey, 1985). However, a low plane of nutrition (insufficient energy

and/or protein) usually induces low male fertility (Martin and Walkden-Brown, 1995),

while severe undernutrition reduced semen quality and scrotal circumference

(Thwaites and Hammond, 1989; Chemineau et al., 1991). Controlled malnutrition in

the form of providing submaintenance diets to sheep during periods of severe feed

shortage is a nutritional exercise which has serious implications on rams reproduction.

Accordingly, a temporal sterility may persist for several weeks and initiation of new

spermatogenic cycle may be delayed before sperm production reaches the maximal

level (Evans and Maxwell, 1987).

It is desirable to improve our understanding of the various physiological

mechanisms which influence fertility of rams. The effect of seasonal changes in

thermal environment and the interaction between thermal load and nutrition warrant

investigation.Therefore, this experiment was designed to investigate the effects of

level of intake of lucerne hay (Medicago sativa), an important tropical legume, on the

physiological responses and seminal traits of Desert rams in different seasons.

3.2 Experimental procedure

The effects of feeding three levels of chopped lucerne hay on

thermoregulation, blood metabolites and semen characteristics were investigated

during tropical winter and summer environmental conditions. Nine entire adult

Desert rams aged 2-3 years and weighing 39.0-46.5 kg have been used in the studies.

They were randomly assigned to 3 groups of 3 rams each, to high, medium and low

level of feeding. The three groups of rams were used in studies performed under

winter and summer climatic conditions. The investigations were carried out for 3

months during winter (December 1999 to March 2000) and summer (June to

September, 2000).The rams were allowed an adaptation period of 2 weeks and were

accommodated individually in two rooms in the animal pens. Appropriate feeding and

watering facilities were used.

The average value for ad libitum levels of dry matter intake for the rams was

considered as the high level of feeding, 100% (1200 gm), and accordingly the

medium level, 66% (800 gm) and the low level , 33% (400 gm) of feeding were

calculated. The amount of food intake was determined by subtracting the refused food

amount from that given. During summer, the same protocol of feeding regimen was

applied. Fresh tap water was continuously available during the experimental period.

The maintenance requirements (Mm) for sheep kept indoors is calculated as

Mm/kg = 1.2 + 0.1 W (body weight) (McDonald et al., 1981). The initial average

body weight of rams obtained was 43.22kg, accordingly the maintenance allowance

was 6.81686 MJ/day.

The metabolizable energy (ME) of lucerne hay in ruminants was calculated as

8.80 MJ/kg (Suleiman and Mabrouk, 1999). The amount of lucerne hay needed to

satisfy the maintenance requirements was computed as 774.84gm. Therefore the

medium level of feeding used in the present

Table 3.1. Experimental plan

Experimental

period Treatment

Daily

measurements

Weekly

sampling and

measurements

Analysis

Winter

(December-

March 2000)

High, medium

and low levels

of feeding

Tr (7:00 a.m.)

Tr (2:00 p.m.)

RR (7:00 a.m.)

Blood

Semen

Body weight

Scrotal

circumference

Blood

metabolites

Semen

characteristics

Summer

(June –

September

2000)

High, medium

and low levels

of feeding

Tr (7:00 a.m)

Tr (2:00 p.m)

RR (7:00 a.m)

Blood

Semen

Body weight

Scrotal

circumference

Blood

metabolites

Semen

characteristics

experiment could provide approximately the maintenance requirements, whereas the

low level of feeding imposed was below maintenance.

The measurements of rectal temperature (Tr) and respiration rate (RR) were

performed daily. Tr was measured at 7:00 a.m. and 2:00 p.m. during winter and

summer for 12 weeks and RR was measured at7: 00 for 9 weeks in each season.The

body weights of rams and scrotal circumference were measured weekly. In each

season, during the experimental period, blood and semen samples were collected

weekly at 8:00 a.m. During each season, blood samples were collected for 12 weeks

and semen samples were obtained for 10 weeks.

Serum samples were used for the determination of the concentrations of total

protein, albumin and urea and plasma samples were used for the determination of

glucose concentration. Semen samples were used for the measurements of ejaculate

volume, mass and individual motility, sperm cell concentration, live sperm (%) and

abnormal sperm (%).The experimental plan is shown in Table 3-1.

3.3. Results

The effects of level of feeding lucerne hay and season on body weight,

thermoregulation, blood metabolites and semen characteristics were studied in Desert

rams. The results obtained are presented as means ± S.E.M.

The prevailing climatic conditions during experimental period are presented in

Table 3.2. The ambient temperature and relative humidity values were higher during

summer compared to the respective values reported during winter conditions.

Table 3.2 The mean values of ambient temperature Ta (ºC) and relative humidity,

RH (%) during the experimental period.

Ta (ºC) Season

Max. Min. Mean

RH (%)

( Mean)

Winter

(December/99 -March/

2000)

31.58

± 1.51

15.83

± 1.66

23.71

± 7.88

28.17

± 4.57

Summer

(June - September /2000)

38.23

± 2.61

25.59

± 1.18

31.91

± 6.32

42.09

± 11.49

3.3.1. Body weight (BW)

Table 3.3 shows the results of the effect of level of feeding lucerne hay and

season on the mean body weight (BW) of rams. The rams fed low level of lucerne hay

maintained significantly lower BW during summer (p< 0.01) and winter (p< 0.001).

All the experimental groups of rams had significantly (p<001) higher values of mean

BW in winter compared to the respective values measured in summer.

3-3-2 Scrotal circumference (SC)

Table 3-4 shows the results of the effects of level of feeding

lucerne hay and season on scrotal circumference. In both seasons, the

rams had significantly (p<0.01) lower scrotal circumference with the low

level of feeding compared to the higher feeding levels. The rams

maintained on high level of feeding had significantly (p<0.01) higher

values of scrotal circumference during winter compared to the values

obtained in summer. However, with medium and low levels of feeding,

the changes related to season did not attain the level of significance. 3.3.3. Thermoregulation

3.3.3.1. Rectal temperature (Tr)

Table 3.5 shows the results of the effect of level of feeding lucerne hay and

season on rectal temperature (Tr) values at 7:00 a.m. Rams fed low level of lucerne

maintained significantly (p<0.05) lower Tr values during winter and summer

compared to the values obtained for the high and medium level groups. However, for

each plane of nutrition, the decrease in Tr during winter did not attain the level of

significance.

Table 3.3 Effects of level of feeding lucerne hay and season on the mean body

weight, BW (kg) of Desert rams .

(n = 36 ,mean ± S.E.M.)

Season Level of feeding

Winter Summer

SL

High A 44.16 a

± 0.33

A 42.16 b

± 0.40 ***

Medium B 39.57

± 0.40a

B 38.40 b

± 0.37 ***

Low B 35.70 a

± 0.39

B 34.45 b

± 0.60 ***

SL ** ***

Mean values within the same row bearing different superscripts (small) are

significantly different.

Mean values within the same column bearing different superscripts (capital) are


SL: Significance level.

** : Significant at p< 0.01.

*** : Significant at p< 0.001.

Table 3.4 Effects of level of feeding lucerne hay and season on scrotal circumference , SC (cm) in Desert rams.

( n = 30 ,mean ± S.E.M.) .

Level of feeding Season SL

Winter Summer

High

A 32.52 b

± 0.40

A 30.75 a

± 0.19 **

Medium

B 30.55 a

± 0.35

AB 29.72 a

± 0.42 NS

Low

B27.77 a

± 0.51

B 28.77 a

± 0.45 NS

SL ** **

Mean values within the same row bearing different superscripts (small) are significantly different.

Mean values within the same column bearing different superscripts (capital) are significantly different.


**: Significant at p<0.01.

NS: Not significant.

Table 3.5 Effects of level of feeding lucerne hay and season on rectal temperature,

Tr (ºC) of Desert rams at 7:00 a.m.

(n = 252, mean ± S.E.M.).


Winter Summer SL

High A 37.98 a

± 0.04

A 38.12 a

± 0.02 NS

Medium A 37.74 a

± 0.05

B 37.89 a

± 0.04 NS

Low B 37.40 a

± 0.06

B 37.54 a

± 0.10 NS

SL * *

Mean values within the same row bearing similar superscripts (small) are not significantly different.



* : Significant at p<0.05.

NS: Not significant

Table 3.6 shows the results of the effect experimental treatments on Tr values

measured at 2:00 p.m. In each season, the rams had significantly (p< 0.01) lower Tr

values with low level of lucerne hay. For each nutritional level, the afternoon Tr value

was significantly (p<0.01) higher during summer compared to the respective winter

value.

The results of the effects of level of feeding lucerne hay and season on the

diurnal pattern of Tr are shown in Table 3.7. The data indicate that during summer,

the afternoon values of Tr were significantly (p<0.001) higher with each level of

feeding compared to the respective values obtained for winter.

3.3.3.2 Respiration rate (RR)

Table 3.8 shows the results of the effect of level of feeding lucerne

hay and season on RR at 7:00 a.m. RR was significantly (p<0.05) lower

with low level of feeding during summer compared to the values reported

for the medium and high levels. All groups of rams showed significantly

(p<0.01) higher RR values during summer compared to respective winter

values.

3.3.4 Blood metabolites

3.3.4.1 Serum total protein

Table 3-9 shows the results of the effects of level of feeding

lucerne hay and season on serum total protein concentration. During

summer, the feeding level had no significant effect on serum total protein

concentration. However, during winter, feed restriction significantly (p<

0.05) lowered serum total protein concentration. For the high level of

feeding, the rams had significantly (p<0.05) lower serum total protein

level during summer compared to the respective value measured in

winter. However, the changes in environment from summer to winter did

not influence the serum

Table 3.6 Effects of level of feeding lucerne hay and season on rectal temperature,

Tr (ºC) of Desert rams at 2:00 p.m.

(n = 252, mean ± S.E.M.).


Winter Summer

SL

High A 38.72 b

± 0.03

A 39.10 a

± 0.05 **

Medium A 38.64 b

± 0.04

A 38.99 a

± 0.06 **

Low B 38.39 b

± 0.04

B 38.76 a

± 0.05 **

SL ** **




**: Significant at p< 0.01.

NS: Not significant

Table 3.7 Effects of level of feeding lucerne hay and season on the diurnal pattern of

rectal temperature, Tr (ºC) of Desert rams.

(n = 252, mean ± S.E.M.).

Level of

feeding Season 7:00 a.m. 2:00 p.m. SL

Summer 38.12 b

± 0.02

39.10 3 a

± 0.05 ***

High

Winter 37.98 b

± 0.04

38.72 a

± 0.03 **

Medium Summer 37.89 b

± 0.04

38.99 a

± 0.06 ***

Winter 37.74 b

± 0.05

38.64 a

± 0.04 **

Summer 37.54 b

± 0.10

38.76 a

± 0.05 ***

Low

Winter 37.40 b

± 0.06

38.39 a

± 0.04 ***

For each season, mean values within the same row bearing different superscripts are




***: Significant at p< 0.001.

Table 3.8 Effects of level of feeding lucerne hay and season on respiration rate, RR

(breaths/min.) of Desert rams at 7:00 a.m.

(n = 189, mean ± S.E.M.) .


Winter Summer

High

A 17.83 b

± 0.24

A 25.02 a

± 0.82 **

Medium

A 18.70 b

± 0.38

A25.40 a

± 0.66 **

Low

A 16.40 b

± 0.28

B 22.39 a

± 0.73 **

SL NS *


Mean values within the same column bearing different superscripts (capital) are not significantly different.


**: Significant at p < 0.01.

*: Significant at p < 0.05.


Table 3.9 Effects of level of feeding lucerne hay and season on serum total protein

concentration (g/dl) in Desert rams.

(n = 36, mean ± S.E.M.).


Winter Summer

SL

High

A 7.84 a

± 1.96

A 7.46 b

± 0.10 *

Medium

B 7.51 a

± 0.10

A 7.43 a

± 0.13 NS

Low

B 7.33 a

± 0.12

A 7.45 a

± 0.14 NS

SL * NS





NS: Not significant

total protein concentration significantly with medium and low levels of

feeding.

3.3.4.2 Serum albumin

Table 3-10 shows the results of the effect of level of feeding

lucerne hay and season on serum albumin concentration. During summer

and winter, the rams fed low level of lucerne hay had significantly

(p<0.05) lower serum albumin level compared to values measured for the

other groups. However, with all levels of feeding, the serum albumin

level was significantly (p<0.05) lower in summer compared to winter

values.

3-3-4-3 Serum urea


lucerne hay and season on serum urea concentration. During summer and

winter, the feeding level had no significant effect on serum urea

concentration. In rams fed low level of lucerne hay, the serum urea

concentration was significantly (p<0.01) higher in summer compared to

the respective value obtained in winter.

3-3-4-4 Plasma glucose


lucerne hay and season on plasma glucose concentration. In both seasons,

the level of feeding did not influence significantly the plasma glucose

concentration. For each level of feeding, the season had no significant

effect on plasma glucose level. However, the values measured during

summer were higher with high and low level of feeding lucerne hay

compared to the respective values obtained in winter.

Table 3.10 Effects of level of feeding Lucerne hay and season on serum albumin

concentration (g/dl) in Desert rams .

(n = 36, mean ± S.E.M).


Winter Summer

SL

High

A 3.57 a

± 0.04

A 3.45 b

± 0.04 *

Medium

B 3.50

± 0.04a

B 3.37 b

± 0.05 *

Low

AB 3.54 a

± 0.04

B 3.38 b

± 0.05 *

SL * *




* : Significant at p<0.05.

Table 3.11 Effects of level of feeding lucerne hay and season on serum urea

concentration (mg/dl)in Desert rams .

(n = 36, mean ± S.E.M.).


Winter Summer

SL

High

A 22.94 a

± 1.11

A 25.46 a

± 1.34 NS

Medium

A 21.38 a

± 0.94

A 25.12 a

± 1.51 NS

Low

A 19.59 b

± 0.71

A 24.59 a

± 1.41 **

SL NS NS


Mean values within the same column bearing similar (capital) superscripts not are not significantly different.



NS: Not significant

Table 3.12 Effects of level of feeding lucerne hay and season on plasma glucose

concentration (mg/dl) in Desert rams .

(n = 36 ,mean ± S.E.M.) .


Winter Summer

High

A 64.91 a

± 2.96

A 67.20 a

± 1.63 NS

Medium

A 62.18 a

± 2.55

A 62.01 a

± 1.38 NS

Low

A 59.74 a

± 2.71

A 61.62 a

± 1.59 NS

SL NS NS

Mean values within the same row and column bearing similar superscripts are not significantly different.


NS: Not significant

3-3-5 Semen characteristics

3-3-5-1 Ejaculate volume


lucerne hay and season on ejaculate volume. In animals fed low level of

lucerne hay, the ejaculate volume was significantly (p<0.01) lower during

summer and winter compared to the values reported for the other groups.

With each level of feeding, the ejaculate volume was higher during winter

compared to the respective summer value. The increase in ejaculate

volume was significant with high and medium levels of feeding (p<0.01)

as well as low level of feeding (p<0.05).

3-3-5-2 Sperm mass motility (MM)


lucerne hay and season on sperms mass motility, MM. During summer,

the sperm MM was significantly (p<0.05) lower with medium and low

levels of feeding. During winter, the level of feeding had no significant

influence on sperm MM. However, with each level of feeding, the sperm

MM was significantly (p<0.001) higher during winter compared to the

respective values obtained during summer.

3-3-5-3 Sperm individual motility (IM)

Table 3-15 shows the results of the effect of level feeding lucerne

hay and season on sperm individual motility, IM. The percentage of

sperm IM was significantly lower with medium and low levels of feeding

g during winter (p<0.01) and summer (p<0.05), respectively. With all

levels of feeding, IM of the sperms was significantly (p<0.001) higher

during winter compared to summer values.

Table 3.13 Effects of level of feeding lucerne hay and season on ejaculate volume

(ml) in Desert rams .

(n = 30, mean ± S.E.M.) .


Winter Summer

SL

High

A 1.96 a

± 0.09

A 1.66 b

± 0.09 **

Medium

A 1.98 a

± 0.10

A 1.58 b

± 0.09 **

Low

B 1.58 a

± 0.08

B 1.33 b

± 0.07 *

SL ** **




*: Significant at p< 0.05.


Table 3.14 Effects of level of feeding lucerne hay and season on sperm mass

motility, M M (0 – 5) in Desert rams.

(n = 30, mean ± S.E.M.) .


Winter Summer

SL

High

A 4.65 a

± 0.08

A 3.66 b

± 1.41 ***

Medium

A 4.42 a

± 0.08

B 2.86 b

± 1.51 ***

Low

A 4.32 a

± 0.10

B 3.02 b

± 1.34 ***

SL NS *




*: Significant at p<0.05.



Table3.15 Effects of level of feeding lucerne hay and season on sperm individual motility, IM (%) in Desert rams .

(n = 30, mean ± S.E.M.).


Winter Summer

SL

High

A 76.67 a

± 2.24

A 59.14 b

± 4.26 **

Medium

B 68.50 a

± 2.90

B 30.71 b

± 4.71 **

Low

B 63.33 a

± 2.84

B 35.15 b

± 4.69 **

SL ** *






3-3-5-4 Sperm cell concentration

Table 3-16 shows the results of the effetcs of level of feeding

lucerne hay and season on sperm cell concentration. During winter, the

rams fed medium level of feeding had significantly (p<0.05) higher

sperms concentration compared to the other levels of feeding. However,

during summer, the rams maintained on low level of feeding had

significantly (p<0.05) higher sperm concentration compared to the other

levels. With all levels of feeding, the sperm concentration was lower

during summer compared to the respective values of winter; however, the

decrease was highly significant (p<0.001) in rams maintained on medium

level of feeding.

3-3-5-5 Incidence of live sperm


lucerne hay and season on live sperm percent. During summer, the value

of live sperm percent was significantly (p<0.05) lower with medium level

of feeding. For each level of feeding, the rams maintained lower live

sperm percent during summer compared to the respective winter value ;

but this change was just significant (p<0.05) with medium plane of

feeding

3-3-5-6 Incidence of abnormal sperm

Table 3-18 shows the results of the effect of level of feeding lucerne hay and season on abnormal sperm percent. During summer, the abnormal sperm percent was significantly (p<0.05) higher with low level of feeding. However, during winter, the level of feeding did not influence the abnormal sperm percent significantly. With all levels of feeding, the abnormal sperm percent was higher during summer. This change was significant with high and medium level of feeding (p<0.05) and low level

of feeding (p<0.001).

Table 3.16 Effects of level of feeding lucerne hay and season on sperm cell

concentration (× 109/ml) in Desert rams.

(n = 30, mean ± S.E.M.).


Winter Summer

SL

High

B 2.07 a

± 0.133

AB 1.64 a

± 0.21 NS

Medium

A 2.37 a

± 0.15

B 1.24 b

± 0.13 ***

Low B 2.15 a A 1.80 b NS

± 0.21 ± 0.21

SL * *







Table 3.17 Effects of level of feeding lucerne hay and season on the incidence of live sperm (%) in Desert rams.

(n = 30, mean ± S.E.M.).


Winter Summer

SL

High A94.80 a A 93.24 a NS

± 1.37 ± 3.40

Medium

A94.97 a

± 0.82

B 87.60 b

± 3.37 *

Low

A94.55 a

± 1.00

A 91.28 a

± 2.14 NS

SL NS *


Mean values within the same column bearing different superscripts (capital) are not significantly different.




Table3.18 Effects of level of feeding lucerne hay and season on the incidence of

abnormal sperm (%) in Desert rams.

(n = 30, mean ± S.E.M.).


Winter Summer

SL

High

A 3.18 b

± 0.60

B 13.07 a

± 4.07 *

Medium

A 5.45 b

± 1.22

B 13.36 a

± 3.29 *

Low

A 3.86 b

± 1.11

A 21.18 a

± 4.03 ***

SL NS *







3.4. Discussion

This experiment aimed to investigate the effects of restriction of

lucerne hay intake and seasonal changes in thermal environment under

tropical conditions on the mean body weight,scrotal circumference,

thermoregulation, blood metabolites and seminal traits of Desert rams.

The results obtained in this study indicate that the physiological responses

and reproductive performance of Desert rams could be modulated by the

essential experimental treatments imposed, the plane of nutrition and

thermal environment.

3.4.1. Body weight (BW )and scrotum circumference (SC)

The results indicate that restriction of intake of lucerne hay induced

significant change in the mean BW of Desert rams in both seasons (Table

3.3). This response clearly reflected the decrease in nutrient intake

associated with feed restriction. The loss in mean BW during feed

restriction is attributed to loss of body reserves usually associated with

depletion of tissue fat and protein. Davis and Hoppel (1986) indicated

that the BW loss during starvation is related to catabolism of muscle

protein. Henry et al. (2000) reported that feed restriction of Corriedale

ewes resulted in lowering of body fat from 36 to 15 % of BW. The loss in

mean BW of Desert rams reported in the present study could also be

attributed to low intake of dry matter during feed restriction. The loss in

BW reported in feed restricted Sonadi and Dorset Horn cross ewes was

associated with low intake of dry matter (Naqvi and Rai, 1991). Feeding

50-70 % of maintenance level of Merino rams resulted in a decrease in

BW (Parker and Thwaites, 1972). The low mean BW reported in the

current results during feed restriction could also be related to decrease in

availability of protein ingested and consequently insufficient microbial

digestion and food utilization. In Manday and Nellore rams, feeding 9.73

% of protein on dry matter basis resulted in an insufficiency in the

achievement of optimum microbial digestion and efficiency of food

utilization (Mohan et al., 1987). Moreover, the loss in the mean BW

reported during feed restriction of Desert rams could also be associated

with a decrease in total body water. Faichney and Gherardi (1986) noted

that water intake in sheep is positively correlated with food intake. Henry

et al. (2000) reported that restriction of lucerne hay intake in Corriedale

ewes was associated with lowering in BW; the authors attributed this

response to low water intake. A low mean BW was also reported in feed

restricted Finnish Landrace and Dorset Horn cross (Alkass et al, 1982),

Merino (Sutama and Edey 1985) and Scottish Black Face and Cheviot

Welsh cross (Wiener et al., 1988) rams.

The significantly higher mean BW observed in all the experimental

groups of rams during winter compared to respective summer values is

closely associated with increase in food consumption and utilization.

Lincoln et al. (2001) suggested a central regulation of long-term cycles in

voluntary food intake. The authors reported that in Soay rams , voluntary

food intake and body weight increased in cold environment; the authors

attributed this response to increase in blood concentration of alpha-

melanocyte stimulating hormone (Alpha-MSH) which is a positive

stimulator of food intake (Henry et al., 2000).

In the current results, the high rate of mean BW loss observed

during summer compared to winter could be attributed to low food intake

at high environmental temperature (Table 3.2). McDonald et al. (2002)

indicated that in sheep, food intake and protein digestion were lower

under high environmental temperature. In Rambouillet ewes, the

reduction in food intake observed at high ambient temperature was

apparently attributed to depression of appetite centre (Moose et al.,

1969). Bhattacharya and Hussain (1974) reported that the food intake and

protein digestibility decreased in Awassi wethers in response to high

environmental temperature and consequently the BW was reduced. El

noutly et al. (1988) observed a significant reduction in dry matter intake

(DMI) in Egyptian Barki and Rahmani ewes during summer compared to

spring and winter; this was attributed to the effects of heat stress.

The current results indicated that feed restriction significantly

reduced the scrotal circumference (SC) of Desert rams in both seasons

(Table 3.4). This response is attributed to general loss in the mean BW

and loss of subcutaneous fat in the scrotal sac. In Merino rams, the SC

was positively correlated with BW (Foster et al., 1989; Murray et al.,

1990 b). In Booroola and Merino rams supplemented with high lupin

grain, a significant correlation between BW and testicular volume was

reported by Martin et al. (1987). Furthermore, Alkass et al. (1982) also

reported lower SC in feed restricted Scottish Black Face and Finnish

Landrace Dorset Horn cross rams.

The higher SC reported during winter for both high and medium

levels of feeding compared to respective summer values could be

attributed to the increase in number of seminiferous tubules and

spermatogenic activity during winter. Foster et al. (1989) and Kealy

(2004) indicated that the SC could be adopted as an index of testicular

weight and ram fertility. In mature Sudanese Hamari rams, Alsayed

(1996) reported relatively higher values of SC during winter

conditions.Islam and Land (1977) reported higher SC values of Finnish

Landrace and Tasmanian rams in temperate zone during the cold season.

3.4.2. Thermoregulation

In this experiment, the rams have been exposed to marked changes

in their thermal environment. The extremes of ambient temperature and

relative humidity reported during winter and summer modulated the

physiological responses of rams to restriction of intake of luceme hay.

The data indicate that reducing the level of feeding influenced the

thermoregulatory response of Desert rams. During both seasons, the rams

exhibited significantly lower rectal temperature (Tr) with low level of

feeding in the morning (Table 3.5) and afternoon (Table 3.6). This

response is clearly associated with a decrease in metabolic heat

production. Previous studies in sheep have reported a decrease in

metabolic heat production in response to feed restriction (Blaxter, 1962;

Graham, 1964; Freetly et al., 2002). Ahmed and Abdelatif (1992)

reported low Tr values in the morning and afternoon in feed restricted

Desert rams under wet summer tropical conditions. The present findings

in Desert rams are in agreement with the results reported by Naqvi and

Rai (1991) in feed restricted Sonadi and Dorset Horn cross ewes.

The significantly higher Tr values obtained in the afternoon during

summer compared to winter values is clearly related to the increase in the

thermal load with rise in ambient temperature during the day. A high

correlation between ambient temperature and Tr was reported during

summer in Egyptian Barki and Rahmani ewes (El nouty et al., 1988)

compared to spring and winter values.

The current results indicate that the diurnal change in Tr observed

in all experimental groups in both seasons (Table 3.7) is associated with

the circadian changes in thermal environment. Also this diurnal change

could be attributed to the higher values of Tr reported in all groups of

rams during summer compared to winter. Piccione and Caola (2003)

indicated that the circadian rhythm of body temperature reflects the

adaptation of animals to changes in external environmental temperature.

In the current study, the diurnal change in Tr of Desert rams was more

pronounced with the low plane of nutrition irrespective of the season.

This response could be related to low metabolic rate of feed restricted

rams associated with low heat production. However, in the current

results, the mean diurnal change in ambient temperature reported during

the experimental period was 15.75ºC during winter and 12.66ºC during

summer. This change in ambient temperature influenced body

temperature of the experimental animals.

Da silva and Minomo (1995) indicated that limited diurnal changes in Tr

of Corriedale rams in the tropics during summer (0.42ºC) and winter

(0.46ºC) were closely related to the prevailing ambient temperature

The data indicate that feed restriction was associated with a

significant decrease in respiration rate (RR) of Desert rams during

summer (Table 3.8).This response is accounted for by a general decline in

metabolism and heat production. The low food intake in rams could have

been associated with a low metabolic rate. Ahmed and Abdelatif (1992)

reported a significant decline in morning values of RR of feed restricted

Hamari rams. Feed restriction of Sonadi and Dorset Horn Cross ewes

decreased the morning values of RR compared to the control (Naqvi and

Rai, 1991).

The significantly higher values of RR observed at 7:00 a.m.

during summer compared to the respective winter values with all levels of

feeding is a recognized response of sheep to the high thermal load during

summer day. Similarly, higher morning RR value was previously

reported during summer under subtropical conditions in Egyptian Barki

and Rahmani ewes (El nouty et al., 1988).

The current results indicated that in both seasons feed restriction

induced decreases in Tr and RR values of Desert rams. It could be

concluded that thermoregulation of Desert rams was influenced by feed

restriction and seasonal changes in thermal environment.

3.4.3. Blood metabolites

The observations made in the present study indicate that the

concentrations of blood metabolites were influenced by the level of

feeding lucerne hay and the thermal environment of the animals. The

rams maintained on low level of feeding showed significantly lower

values of serum total protein concentration during winter compared to

summer values (Table 3.9). Swenson (1993) indicated that the synthesis

of plasma proteins is markedly reduced in prolonged dietary deficiency

when the supply of amino acids for digestive process is not adequate. In

feed restricted Merino rams, Setchell et al. (1965) reported low levels of

total plasma protein. The current results confirm the findings reported

previously by Ahmed and Abdelatif (1992) in Desert rams fed 68% of

their ad libitum level of luceme hay intake. Naqvi and Hooda (1991)

observed lower serum protein concentration in Malpura and cross

Avikalin non-pregnant ewes fed 30% of ad libitum intake of hay and

concentrate ration

In the present study, the significantly lower serum albumin concentration obtained with feed restriction in both seasons in Desert rams (Table 3.10) is clearly associated with

the low amount of lucerne hay consumed and consequently the amount of protein intake. The current results are

consistent with the findings of Ahmed and Abdelatif (1992) who reported a reduction in plasma albumin level in Desert rams during feed restriction under wet summer conditions. The results have shown that with all levels of feeding,

the serum albumin level was lower during summer compared to winter values. This finding could be related to the low intake of lucerne hay during summer compared to

winter. The response could also be associated with an increase in water consumption during summer and

development of haemodilution. However, in Sudanese Desert ewes, the serum albumin level was not influenced by

seasonal changes in thermal load (Alsayed, 1997). In the current study, the serum urea level was

significantly higher during summer compared to winter values in rams fed low level of lucerne hay (Table 3.11). This

response could be related to low water intake. Previous studies have reported a positive correlation between water

intake and dry matter intake in sheep (Kamphus, 2000) and a decrease in urinary nitrogen excretion during water

restriction (Aganga, 1992). Furthermore, the restriction of food intake could have been associated with recycling of

urea and reduction in urinary excretion. Bunting et al. (1992) reported an inverse relationship between the level of

protein intake and the amount of blood urea nitrogen entering the rumen. Also Farid (1985) attributed reduction

in urinary nitrogen excretion in Barki rams fed 60% of their maintenance requirement to improved utilization of digested

nitrogen. Conversely low plasma urea levels in response to food restriction have been reported in Desert rams (Ahmed

and Abdelatif, 1992) and Sonadi and Dorset Horn cross rams (Naqvi and Rai, 1991). However, Herny et al. (2000) noted that feed restriction had no significant influence on

plasma urea level in ovariectomized Corriedale ewes. In the present study, in both seasons, the plasma

glucose level was decreased slightly with lowering of the level of intake of lucerne hay (Table 3.12). This response

could be attributed to decrease in availability of nutrients and lower rate of production of propionate which is known

to be the main precursor of glucose in ruminants (Bergman, 1973,1990; Trenkle, 1981;). The low plasma glucose level

obtained in feed restricted rams could also be attributed to the low amount of protein intake as a proportion of glucose is derived from amino acids by gluconeogenesis (Reilly and

Ford, 1971). This response confirms previous reports in Desert rams (Abdelatif and Ahmed, 1992), Sonadi and Horn

Cross rams (Naqvi and Rai, 1991) and Malpura and cross Avikalin non- pregnant ewes (Naqvi and Hooda, 1991).

Hypoglycaeamia was also reported in Suffolk wethers fed on submaintenance energy allowance (Moloney and Moore,

1994). 3.4.4. Semen characteristics

The current results suggest that the seminal traits in Desert rams were influenced by lowering of the plane of

nutrition and seasonal changes in the thermal environment. In most mammals, the process of spermatogenesis and

Sertoli cell multiplication are influenced by seasonal changes of environmental temperature through the central nervous

system (Hotzel et al., 2003). In temperate breeds of rams, Smith et al. (1999) reported seasonal change in the total

protein concentration of seminal plasma, with higher levels obtained during the breeding season. For Desert rams,

previous studies indicated seasonal effect on their reproductive performance and seminal traits (Galil and

Galil, 1982 a,b; Alsayed, 1996) with decline in semen quality during summer accounted for by thermal influence.

The current study is unique in that it investigated the interaction between the plane of nutrition and seasonal

change in thermal environment on seminal traits of Desert rams. This approach is rather realistic as it attempts to

simulate the nutritional and climatic stresses experienced by animals under natural tropical conditions.

The ejaculate volume was significantly lower with the low level of feeding in both seasons (Table 3.13). This

response is apparently associated with the influence of low plane of nutrition on endocrine response in rams. Brown

(1994) indicated that during feed restriction of Merino rams, low concentration of luteinizing hormone (LH) resulted in

reduction of testosterone secretion. The low ejaculate volume of food restricted rams could be attributed to

decrease in the function of pituitary gland and testes Alkass et al. (1982) reported a decrease in the size of pituitary gland

and testes in feed restricted rams. Consequently, the concentration of LH and its action on Leydig cells to release

testosterone is reduced. A low testosterone level is usually associated with reduction in testicular, epididymal and accessory genital glands secretions which contribute to

seminal fluid. The low ejaculate volume obtained with low level of feeding could be related mainly to a decrease in the

accessory genital glands, secretions associated with endocrine changes. The androgen dependent seminal

vesicles contribute 50% of the seminal plasma volume in ruminants (Jainudeen and Hafez, 2000).

In the tropic, the day length is shorter during winter compared to summer. However, it is unlikely that

photoperiodism has influenced the observed seasonal changes in the ejaculate volume of Desert rams. The

significantly higher ejaculate volume observed during winter with all levels of feeding could be related to stimulatory

effects of testosterone. Kajihera et al.(1972) indicated that the reproductive endocrine response in mammals involves activation of the pituitary gland and consequent activation

of the accessory genital glands by testosterone under the control of LH. Seasonal changes in testosterone secretion

and ejaculate volume were reported in Hampshire rams in temperate environment (Purvis et al., 1974) and in Finn

cross rams under subtropical conditions (Amir and Volcani, 1965b). The high ejaculate volume of Desert rams reported

in winter in the current study is likely to be related to the effects of exposure to cold environment associated with

endocrine activation. The current findings are in agreement with the observations made by Galil and Galil (1982a) and

Alsayed (1996) in Desert rams, reporting high ejaculate volumes during winter. However, the high volumes of

ejaculates obtained could be related to breed characteristic. Alsayed (1996) reported an ejaculate volume of 2.2ml in

Hamari Desert rams. In the present study, the sperm mass motility (MM)

was significantly lower with feed restriction during summer (Table 3.14). This is clearly related to decline in the

nutritional status of the rams. Howland (1975) noted that the seminal plasma metabolites are drawn from blood

metabolites. Amir and Volcani (1965a) indicated that the fructose level in seminal plasma is an indicator of the nutritional status of Awassi rams. Moule et al. (1996)

reported low fructose concentration in ejaculates of Merino

and Romney Marsh rams fed 30% of energy intake. In the current study, the low food intake during summer could

have induced low fructose level in seminal plasma and consequently decreased mass motility of spermatozoa.

However, Galil and Galil (1982b) reported a low level of fructose in seminal plasma of Desert rams during summer

and attributed this to high ambient temperature and reduced secretion of testosterone hormone. Chahal et al. (1979) indicated that during summer, fructose level and

sperm MM were positively related and reduced sperm motility could be related to low metabolic rate of

spermatozoa. The authors also indicated that the reduction in fructose level could be related to the reduction in seminal

vesicles, activity in response to low blood levels of LH and testosterone. The reduction in sperm MM could also be

partly associated with the low serum albumin concentration reported in the current study in feed restricted rams.

Miyamoto and Chang (1973) suggested that serum albumin is the best medium for increasing the proportion of motile

sperms in vitro with increased capacitation and fertilization. Smith et al. (1999) noted a poor maintenance of sperm

motility in rams with low seminal plasma proteins. The low sperm MM observed in the current study could be

associated with the low fructose level in feed restricted rams as well as albumin concentration.

The significantly lower sperm mass motility (MM) observed with all levels of feeding during summer compared

to winter (Table 3.14) could be related to exposure of the testes and epididymal sperm reserve to high ambient

temperature. Also the low sperm MM could be related to the high body temperature of rams reported in the current

results during summer compared to winter (Table 3.6). In Desert rams, Galil and Galil (1982a) reported a decrease in

sperm MM during summer compared to winter. The results have shown that in both seasons, the

medium and low level of feeding were associated with a significant reduction in sperm individual motility IM (Table

3.15). The low IM value could be attributed mainly to low plane of nutrition and protein intake. Also it could be

related to relatively low concentration of seminal plasma metabolites accompanied by thermal stress during summer. Pratt and Wettemann (1986) noted that the activity of thyroid gland in sheep was depressed during heat stress. In

thyroidectomized Merino rams Chandraseckhar et al. (1986) related low sperm IM to a decline in sex hormone binding

globulins. The progressive motility which is acquired in the epididymis involves activation of a unique protein called

CatSper, which is localized to the principal piece of the sperm tail. This protein appears to be Ca+2 ions channel that

permits cAMP-generalized Ca+2 influx (Ganong, 2003).The reduction is sperm IM could also be associated with low

activity of pituitary gland under feed restriction conditions. In Merino and English Leicester rams, food restriction was

associated with low weights and secretions of seminal vesicles which are controlled by LH secretion (Setchell et al.,

1965). The authors also reported low seminal plasma fructose concentration and a decline in sperm IM.

Therefore, the low sperm IM observed in Desert rams in the current study is likely to be related to low blood metabolites

observed and the depressed activity of endocrine glands in response to feed restriction. However, during summer,

thermal stress had a role in lowering IM.

The results indicate that irrespective of the level of feeding, the

sperm IM was significantly higher during winter compared to summer

values (Table 3.15). This finding could be associated with the efficiency

of the cremaster muscle and tunica dartos in the maintenance of testicular

thermoregulation during winter, which provided favourable medium for

sperms to acquire motility during epididymal transit and preservation.

High values of sperm IM were previously reported in Desert rams during

winter and autumn compared to summer (Galil and Galil, 1982a).

The results obtained indicate that the rams had higher sperm

concentration with the medium level of feeding during winter (Table

3.16). This response could be associated with the low ejaculate volume

obtained with low levels of feeding compared with the high level group,

and the fact that ejaculate volume depends primarily upon the secretion of

seminal plasma rather than sperm concentration (Howland, 1975).

However, Brown (1994) noted that the influences of nutrition on

reproductive process in rams are mediated via effects of dietary

constituents on the hypothamic- pituitary axis. The author also indicated

that the nutritional regime can alter androgen activity without necessarily

affecting spermatogenesis as certain constituents of the diet can

differently affect the production of and /or the release of LH and FSH.

However, the low sperm concentration reported during summer with the

medium level of feeding could be associated with the increase in ambient

temperature. The present findings regarding sperm cell concentration are

consistent with the results reported previously in feed restricted Merino

rams (Parker and Thwaites, 1972) and Scottish Black Face and Finnish

Landrace cross rams (Alkass et al., 1982).

It is evident that the sperm cell concentration was lower with all levels of feeding during summer compared to

winter (Table 3.16), particularly in rams maintained on medium level of feeding. This observation indicates that the magnitude of change in sperm cell concentra-tion in Desert

rams is influenced by seasonal changes in thermal environment and feed restriction. This could be related to a decrease in spermatogenic activity and epididymal reserve during the hot season due to spermatogenic degeneration.

Similarly a lower sperm concentration was reported in Desert rams during summer compared with winter values

(Galil and Galil, 1982a). In the current study, lower live sperm values were

obtained during summer compared to winter values,

particularly in the group of rams maintained on medium level of feeding (Table 3.17). This response could be related to the increase in body temperature resulting in increase in metabolic activity of testicular cells leading to hypoxia and

disturbance of spermatogenesis. Chahal et al. (1979) reported low live sperms percent in Corriedale rams during

summer and attributed this to testicular hypoxia which probably plays a role in heat-induced spermatogenic disturbance. In Desert rams, Galil and Galil (1982a)

reported low live sperms percent during summer. However, reduction in live sperm percent in association with feed

restriction could be attributed to the reduction in number of seminiferous tubules and increase in dead sperm percent

due to increase in degenerative process. Feed restriction increased significantly the incidence of abnormal

sperms during summer (Table 3.18). This response is associated with a

decrease in availability and supply of essential nutrients required for

sperm production in the testis and epididymal maturation accompanied

with thermal stress during summer. Setchell et al. (1965) reported low

nutrient supply of testicular and epididymal tissues in feed restricted

Merino and English Leicester rams. Feed restriction has also an androgen

dependant effect on sperm maturation during epididymal transit resulting

in immature sperm of protoplasmic droplet (Chardraseckhar et al. 1985).

Feed restriction of Merino rams increased abnormal sperm percent

(Sutama and Edey, 1985), while severe feed restriction resulted in

permanent damage to gonadal tissues of Merino rams (Brown, 1994).

Young et al. (2000) reported apoptotic testicular degeneration in feed

restricted mice.

The current results indicate that with all levels of feeding, the

abnormal sperm percent was higher during summer compared to winter

values (Table 3.18). This could be accounted for by the high body

temperature reported in this study during summer and the impairment of

thermoregulation capacity of the scrotum in the hot environment. Sailer

et al. (1997) indicated that in mammals, testicular hyperthermia disturbed

spermatogenesis. The authors also indicated that epididymal sperms are

susceptible to acid induced DNA denaturation and minor chromatin

abnormalities.However, Lue et al. (2002) noted that testicular

hyperthermia in rats induces stage specific and germ cell–specific

apoptosis, azoospermia and oligospermia. Other studies have reported

that increased testicular temperature provokes testicular degeneration and

increases the percent of abnormal sperms (Mieusset et al., 1991;

Mieusset et al., 1992; Kastelic et al., 1997; Love and Kenney, 1999;

Kastelic et al., 2000; Ibrahim et al., 2001). The testicular degenerations

observed during summer in temperate breeds of rams are associated with

seasonal sterility of rams. Karagiannidis et al. (2000) reported high

percent of abnormal sperms of Friesian and Chios rams during the hot

season in the suptropics. However, in the tropics, thermal stress rather

than seasonal changes has detrimental effect on sperm abnormalities.

Galil and Galil (1982) reported high abnormal sperm percent in Desert

rams during summer. It could be concluded that regardless of the

nutritional status of Desert rams, summer heat increased the percentage of

abnormal sperms.

3.5. Summary

1. Nine entire Desert rams were used to study the effects of the level

of feeding lucerne hay (high,medium and low) and season (winter

versus summer) on mean body weight (BW), scrotal

circumference (SC), thermoregulation, blood metabolites and

seminal traits.

2. The mean BW of rams was significantly lower in feed restricted

rams in both seasons. For all the experimental animals, the mean

BW was significantly higher during winter compared to summer

values.

3. The SC of rams maintained on low level of feeding was

significantly lower regardless of season.

4. The rectal temperature (Tr) was lower in feed restricted rams in

the morning and afternoon in both seasons. During summer, Tr

values in the afternoon were significantly higher compared to

respective winter values; there were significant diurnal changes in

Tr in both seasons.

5. During summer, at 7: 00 a.m. the respiration rate (RR) was

significantly lower with the low level of feeding.

6. The serum total protein level was significantly lower in feed

restricted rams during winter compared to the control group. The

serum albumin level decreased significantly with feed restriction

during both seasons. All the experimental groups had lower serum

albumin concentration during summer compared to winter

values.The rams maintained on low level of feeding had higher

serum urea concentration during summer compared to winter.

7. The ejaculate volume was significantly lower with low level of

feeding during both seasons. All the experimental animals

showed a significantly lower ejaculate volume during summer

compared to winter.

8. The sperm mass motility (MM) was significantly lower with low

level of feeding during summer. All the experimental animal

showed a significantly higher sperm MM during winter compared

to summer values.

9. The sperm individual motility (IM) was significantly lower in

rams maintained on low level of feeding regardless of season. The

sperm IM was significantly lower during summer compared to

winter values , irrespective of the level of feeding .

10. The sperm cell concentration was significantly higher with feed

restriction in both seasons. With medium level of feeding, it was

significantly lower during summer compared to winter value.

11. The live sperm percent was significantly lower during summer

with the medium level of feeding compared to the respective

groups, values. Also the medium level group had significantly

lower live sperm percent during summer compared to winter

values.

12. The abnormal sperm percent was significantly higher with low

level of feeding compared to the higher level of feeding. During

summer, the abnormal sperm percent was significantly higher

with all levels of feeding compared to values obtained during

winter.

CHAPTER FOUR EFFECTS OF EXPOSURE TO SOLAR RADIATION ON

THERMOREGULATION, BLOOD COMPOSITION AND SEMEN

CHARACTERISTCS 4.1 Introduction

In the tropical environment, solar radiation constitutes a critical factor in the

animal’s energy budget (Mitchell, 1977). High intensity of solar radiation during the

day and reradiation from the surroundings during the night produce fluctuations in

thermal environment and animal body temperature (Mount, 1979). The solar cycle has

marked consequences for the climatic environment and animals have adapted to use

temperature and photoperiod as hints to trigger reproductive activity (Haynes and

Howles, 1981).

The range of environmental conditions under which sheep are kept for

production is extremely wide. The thermal environment influences the utilization of

food, energy requirements and the physiological means by which sheep can adjust

their metabolism (Graham et al., 1959).When sheep are moved to a new thermal

environment, adjustments of their heat loss mechanisms occur.In a considerably

higher environmental temperature, the body temperature increases and heat stress

develops when the total heat gain exceeds the heat loss capabilities of sheep (Hahn

and Becker, 1984). Sheep adjust their physiological means of heat disposal mainly by

the evaporative cooling mechanisms to maintain their deep body temperature

(McArthur, 1980 ;Da Silva et al. 2002). In severe thermal stress, sheep react by

reducing food intake, increasing water intake (Terrill, 1968; Robertshaw, 1981) and

reducing faecal and urinary water loss (Macfarlane, 1981).

In all domestic mammals, spermatogenesis is depressed at body temperature

and male gametes fail to tolerate the increase in body temperature(Arthur et al.,

1985).Extremely high environmental temperature has an immediate effect on

spermatogenesis, in contrast to moderately high environmental temperature extending

over several months, which show a delayed effect (Jainudeen and Hafez, 2000).

In the tropics, under the nomadic system of sheep rearing, heat stress affects

the physiological responses and productive abilities (Johnson, 1987). Under this

extensive system, the reproductive performance of rams is influenced by thermal load

(Yeates et al., 1975b; Kastelic et. al ,1997), as they have to combat heat and serve

females throughout the year. Accordingly, the purpose of this experiment was, firstly,

to investigate the effects of exposure to direct solar radiation on the physiological

responses and semen characteristics in Desert rams. The second objective was to

asses the effect of exposure to solar heat load on the responses of rams to the

frequency of ejaculation of semen.


The experimental plan is presented in Table 4-1 .Eight entire Desert rams were

randomly assigned to two groups of 4 rams each. Group A was kept under shade

(shaded), and group B was exposed to direct solar radiation (unshaded). Both groups

of rams were allowed an adaptation period of 2 weeks, followed by 5 weeks of

experimental period. Throughout the adaptation and experimental periods, the

animals were fed chopped lucerne hay and were given tap water ad libitum.

During the first three weeks of experimental period, for both shaded and

unshaded groups of rams, the measurements of rectal temperature (Tr) and respiration

rate (RR) were carried out twice daily, at 7:00 a.m. and 2:00 p.m. During this period,

blood and semen samples were collected weekly

Table 4.1 Experimental plan

Experimental

period

Experimental

groups

Daily

measurements

Weekly

sampling Measurements

The first 3 weeks

(25Oct.-15 Nov.)

Shaded (A)

Unshaded (B)

Tr: (7:00 a.m.

2:00 p.m).

RR: (7:00 a.m.

2:00 p.m).

Daily Sampling

-Blood

- Semen

-Scrotal

circumference

-Blood

composition

-Semen

characteristics

The last week

(22-28 Nov.)

A and B

alternatively

Semen samples

for 3 consecutive

days

Blood samples

before the first

collection of

semen and after

the last one

-Blood

composition

-Semen

characteristics

at 8:00 a.m. The measurement of scrotal circumference was also performed weekly.

In the 4th and 5th week of experimental period, the exhaustion test was

performed for both groups of rams alternatively. In this treatment, semen samples

were collected every 30 min. from each ram in three consecutive days. During the

exhaustion test, for each ram, blood samples were drawn before the collection of the

first semen sample and after the last one. The unshaded group was represented by 3

rams only during the exhustion test due to the sudden death of one ram.

In the first day of exhaustion test, in the control group, all rams ejaculated and

2 rams ejaculated up to 6 collections. However, on the second day, one ram failed to

ejaculate, and up to 5 collections were obtained from two rams. In the third day, two

rams ejaculated up to 6 collections; however, one ram failed to ejaculate. For the

unshaded rams, on the first day all the rams ejaculated and 2 rams ejaculated up to 5

collections. On the second day, all the rams ejaculated and one ram ejaculated up to 6

collections. However, in the third day one ram failed to ejaculate, and up to 4

collections were obtained from 2 rams.

Blood samples were used for the determination of the PCV and leukocytic

indices. Serum samples were used to determine the concentrations of total protein,

albumin and urea, and plasma samples were used for the measurement of glucose

concentration. The semen samples were used for the determination of ejaculate

volume, and the analysis of mass and individual motility, sperm concentration, live

and abnormal sperms percent and semen pH.

4.3. Results

The effects of exposure to solar radiation on thermoregulation, blood

composition and semen characteristics and the effects of exposure to solar radiation

and exhaustion test on blood composition and semen characteristics were investigated

in Desert rams. The results obtained are presented as mean ± S.E.M.

The data for the prevailing climatic conditions during the experimental period

are shown in Table 4.2.

4.3.1. Effects of exposure to solar radiation

4.3.1.1. Thermoregulation

4.3.1.1.1. Rectal temperature (Tr)

Table 4.3 shows the results of the effect of exposure to solar radiation on the

mean values of rectal temperature (Tr) of rams measured at 7:00 a.m. In both groups

of rams, Tr increased in the last two weeks of the experimental period. The Tr value

measured in the second week for the unshaded rams was significantly (p<0.05)

higher. However, compared to the shaded rams, Tr was slightly higher in the

unshaded group of rams during the experimental period .

Table 4.4 shows the results of the effect of exposure to solar radiation on Tr

measured at 2.00 p.m. In the shaded group, Tr decreased slightly in the second week

and maintained the initial level in the third week. The group of rams exposed to solar

radiation had a significantly (p<0.05) higher Tr value in the first week compared to

values obtained in weeks 2 and 3. The rams exposed to solar radiation had

significantly

Table 4.2 The prevailing climatic conditions during the experimental

period (25 October – 28 November /2000).

Temperature (ºC) Time

(weeks) Max. Min. Mean

RH (%)

(Mean)

1 35.6 19.7 27.7 23

2 38.5 20.6 29.6 25

3 36.5 20.2 28.4 26

4 32.9 18.0 25.5 39

5 34.2 15.9 25.1 30

Mean

± SE

35.15

±1.40

18.9

±1.7

27.26

±1.72

28.6

±5.68

Solar radiation: 377 W/m2

Table 4.3 Effect of exposure to solar radiation on rectal temperature, Tr (ºC)

of Desert rams at 7: 00 a.m.

(n = 12, mean ± S.E.M.).

Time

(weeks) Shaded Unshaded SL

1

A 38.18 a

± 0.29

B 38.25 a

± 0.39

NS

2 A 38.48 a

± 0.10

A 38.95 a

± 0.30 NS

3 A 38.48 a

± 0.06

B 38.88 a

± 0.11 NS

SL NS *

Mean values within the same row bearing similar superscripts (small) are not




SL : Significance level.

* : Significant at p < 0.05.

NS: Not significant

Table 4.4 Effect of exposure to solar radiation on rectal temperature, Tr (ºC)

of Desert rams at 2: 00 p.m.

(n = 12, mean ± S.E.M.).

Time


1

38.80 b

± 0.10

A 39.98 a

± 0.27

***

2

A 39.28 a

± 0.19

B 39.68 a

± 0.23 NS

3

A 38.83 a

± 0.11

B 39.30 a

± 0.40 NS

SL NS *







*** : Significant at p< 0.001.


(p<0.001) higher Tr compared to the shaded group only in the first week. Both

groups of rams showed a diurnal pattern in Tr which was more pronounced in animals

exposed to solar radiation.

4.3.1.1.2 Respiration rate (RR)

Table 4.5 shows the results of the effect of exposure to solar radiation on RR

at 7:00 a.m. In the shaded groups of rams, RR was significantly (p<0.05) higher in the

second week compared to values obtained in the first and third week. However, in the

unshaded rams, RR was significantly (p<0.05) higher in the last two weeks

compared to the value obtained for the first week. The rams exposed to solar

radiation maintained significantly higher RR values compared to the control in the

first and second week (p< 0.05) and in the third week (p< 0.01).

Table 4-6 shows the results of the effects of exposure to solar radiation on RR

at 2.00 p.m. In both groups of rams, RR tended to increase progressively during the

experimental period. The change in RR was significant for the shaded (p<0.05) and

unshaded (p<0.01) group of rams. The unshaded group of rams maintained

significantly higher values of RR compared to the shaded group in the first week

(p<0.001) and in the second and third week (p<0.01). The changes in RR in both

groups showed a diurnal pattern which was more pronounced in the unshaded group

of rams.


4.3.1.2.1 Packed cell volume (PCV)

Table 4.7 shows the results of the effects of exposure to solar radiation on

PCV level. In both groups of rams, there was no significant changes in PCV level

during the experimental period. Also the results did not reveal any significant effect of

exposure to solar radiation on PCV

Table 4.5 Effect of exposure to solar radiation on respiration rate, RR (breaths/min)


(n = 12 , mean ± S.E.M.).

Time


1

B 22.15 b

± 0.29

B 24.42 a

± 1.12

*

2

A 26.20 b

± 0.97

A 29.28 a

± 0.69 *

3

B 23.83 b

± 0.91

A 28.50 a

± 1.54 **

SL * *







** : Significant at p <0.01.

Table 4.6 Effect of exposure to solar radiation on respiration rate, RR(breaths/min)

of Desert rams at 2: 00 p.m..

( n = 12 ,mean± S.E.M.).

Time


1

B32.98 b

± 1.55

B78.30 a

± 7.03

***

2

AB57.73 b

± 5.89

A 109.78 a

± 9.17 **

3

A71.75 b

± 0.85

A108.55 a

± 8.82 **

SL * **







** : Significant at p < 0.01.

*** : Significant at p < 0.001.

Table 4.7 Effects of exposure to solar radiation on the PCV (%) in Desert rams.

(n = 12 , mean ±S.E.M.).

Time


1

A26.75 a

± 1.31

A26.75 a

± 1.25

NS

2

A24.00 a

± 0.71

A22.25 a

± 1.65 NS

3

A27.00 a

± 1.58

A23.00 a

± 2.27 NS

SL NS NS

Mean values within the same row and column bearing similar superscripts are

not significantly different.


NS: Not significant

level. However, during the second and third week of the experimental period, the

rams exposed to solar radiation maintained lower values of PCV.

4.3.1.2.2 Leukocytic indices

Table 4.8 shows the results of the effects of exposure to solar radiation on total

leukocyte count (TLC). For both groups, there was no significant change in TLC

during the experimental period. Also the exposure to solar radiation did not elicit any

significant effect on TLC.


differential leukocyte count (DLC). For lymphocytes, there was no significant change

during the experimental period for the shaded and unshaded group of rams. Also the

exposure to solar radiation was not associated with a significant change in the ratio of

lymphocytes.

There was no significant change in the ratio of neutrophils in the shaded group

of rams. However, in the unshaded group, the ratio of neutrophils was significantly

(p< 0.05) higher in the first week of exposure to solar radiation compared to the

values obtained in the second and third week. There was no significant difference in

the ratio of neutrophils between the shaded and unshaded rams.

For each group of rams, there was no significant change in the ratio of

eosinophils during the experimental period. However, for the shaded group of rams,

there was an increase in the ratio of eosinophils in the third week and for the unshaded

group, there was a slight decrease. The exposure to solar radiation did not affect the

ratio of eosinophils in the first and second week; in the third week, the unshaded

group had significantly (p<0.05) lower ratio of eosinophils compared to the shaded

group.

Table 4.8 Effect of exposure to solar radiation on total leukocyte count,

TLC (×103/µl) in Desert rams.

(n = 12, mean± S.E.M.).

Time


1

A5.86 a

A5.88 a NS

± 0.30 ± 0.66

2

A6.15 a

± 0.45

A7.54 a

± 0.61 NS

3

A8.08 a

± 0.15

A7.64 a

± 0.90 NS

SL NS NS





Table 4.9 Effect of exposure to solar radiation on differential leukocyte count ,

DLC in Desert rams.

(n = 12 , mean± S.E.M.).

Cell type

(%)

Time


1

A 56.25 a

± 4.21

A 52.75 a

± 5.39

NS

2 A 64.50 a

± 2.02

A 55.75

± 6.61 NS

3 A 61.75 a

± 0.63

A 63.75 a ± 1.38

NS

Lymphocytes

SL NS NS

1 A 37.00 a

± 4.45

A 41.05 a ± 5.73

NS

2 A 28.75 a

± 1.97

B 29.76 a

± 0.63 NS

3 A 28.75 a

± 1.25

B 29.00 a ± 1.47

NS

Neutrophils

SL NS *

1 A 3.25 a

± 0.48

A 3.50 a

± 0.65 NS

2 A 2.25 a

± 0.63

A 3.00 a

± 0.01 NS

3 A 5.50 a

± 1.55

A 2.25 b ± 0.25

*

Eosinophils

SL NS NS

1 A 3.50 a

± 0.50

B 2.75 a

± 0.48 NS

Monocytes

2 A 4.75 a

± 0.25

A 4.50 a

± 0.50 NS

3 A 3.75 a

± 0.75

A 4.50 a ± 0.50

NS

SL NS *







In the control group, there was no significant change in the ratio of monocytes during

the experimental period, but in the group exposed to solar radiation, there was a

significant (p< 0.05) increase in the ratio of monocytes in the second and third week

of the experimental period. Exposure to solar radiation did not affect the ratio of

monocytes during the experimental period.

4.3.1.2.3 Serum total protein

Table 4.10 shows the results of the effects of exposure to solar radiation on serum total protein concentration. In the shaded group of rams, the serum total protein level decreased significantly (p< 0.05) in the third week of the experimental period. In the group of rams exposed to solar radiation, there was no significant change in total protein concentration during the experimental period. The exposure to solar radiation increased the total protein concentration significantly (p< 0.05) only in the third week of the experimental period compared to the respective value

obtained for the shaded rams. 4.3.1.2.4 Serum albumin

Table 4.11 shows the results of the effects of solar radiation on serum albumin

concentration. During the experimental period, both groups showed a gradual

insignificant decrease in serum albumin concentration. In the second week, the serum

albumin level was significantly (p< 0.05) lower in the group exposed to solar

radiation compared to the value obtained for the shaded group.

4.3.1.2.5 Serum urea

Table 4.12 shows the results of the effects of solar radiation on serum urea

concentration. In both groups of rams, there was a significant (p< 0.05) decrease in

serum urea level during the experimental period.

Table 4.10 Effect of exposure to solar radiation on serum total protein concentration

(g/dl) in Desert rams.

(n =12, mean ± S.E.M.).

Time


1

A7.58 a

± 0.40

A7.30 a

± 0.14

NS

2

A7.53 a

± 0.19

A7.78 a

± 0.36 NS

3

B6.63 b

± 0.25

A7.73 a

± 0.33 *

SL * NS



Mean values within the same column bearing different superscripts (capital)

are significantly different.


* : Significant at p <0.05.

NS: Not significant .

Table 4.11 Effect of exposure to solar radiation on serum albumin concentration

(g/dl) in Desert rams .

(n = 12, mean± S.E.M.).

Time


1

A3.85 a

± 0.40

A3.63 a

± 0.10

NS

2

A3.80 a

± 0.11

A3.50 b

± 0.07 *

3

A3.70 a

± 0.11

A3.48 a

± 0.06 NS

SL NS NS



Mean values within the same column bearing similar superscripts (capital) are


Table 4.12 Effect of exposure to solar radiation on serum urea concentration

(mg/dl) in Desert rams .

(n = 12, mean± S.E.M.).

Time


1

B24.15 a

± 1.93

A28.48 a

± 2.19

NS

2

A30.10 a

± 2.44

A24.05 a

± 2.63 NS

3

B18.50 a

± 1.97

B17.80 a

± 2.43 NS

SL * *








There was no significant effect of exposure to solar radiation on serum urea level

measured at weekly intervals during the experimental period.

4.3.1.2.6 Plasma glucose

Table 4.13 shows the results of the effects of solar radiation on plasma glucose

concentration .There was a significant decrease in plasma glucose level of the shaded

(p<0.05) and unshaded (p<0.01) group of rams in the third week . In the first and

second week, there was no significant difference in plasma glucose level between

the two groups . In the third week, the unshaded group of rams had significantly (p<

0.05) lower plasma glucose level compared to the value obtained for the shaded

group.


4.3.1.3.1 Ejaculate volume

Table 4.14 shows the results of the effect of solar radiation on the ejaculate

volume. In the shaded group of rams , the ejaculate volume was significantly (p<0.05)

higher in the second and third week of the experimental period. In the group of rams

exposed to solar radiation, the ejaculate volume decreased significantly (p<0.05) in

the third week. The ejaculate volume was significantly (p < 0.05) higher in the

ushaded group of rams compared to the respective value obtained for the shaded

group in the second week.

4.3.1.3.2 Sperm mass motility (MM)


sperm MM. In the shaded group of rams, the sperm MM was significantly (p<0.05)

lower in the third week of the experimental period. For rams exposed to solar

radiation, the sperm MM tended to decrease

Table 4.13 Effect of exposure to solar radiation on plasma glucose concentration

(mg/dl) in Desert rams.

(n = 12,mean ± S.E.M.).

Time


1

A 81.55 a

A 81.80 a NS

± 5.04 ± 6.02

2 A 85.63 a

± 2.03

A 85.10 a

± 2.66 NS

3 B 74.15 a

± 3.55

B 56.80 b

± 3.44 *

SL * **







**: Significant at p <0.01.


Table 4.14 Effect of exposure to solar radiation on ejaculate volume (ml)

in Desert rams.

(n = 12,mean± S.E.M.).

Time


1

B1.88 a

± 0.18

A2.80 a

± 0.63

NS

2 A2.22 b

± 0.53

A2.55 a

± 0.26 *

3 A2.38 a

± 0.65

B2.23 a

± 0.32 NS

SL * *





SL: Significance level. .


NS: Not significant

Table 4.15 Effects of exposure to solar radiation on sperm mass motility , MM

(0 – 5) in Desert rams.

( n =12 ,mean± S.E.M.).

Time


1

A3.75 a

± 0.14

A4.25 a

± 0.14

NS

2 A4.00 a

± 0.00

B3.25 a

± 0.48 NS

3 B3.13 a

± 0.31

B2.88 a

± 0.31 NS

SL * *








progressively during the experimental period, and the values obtained in the second

and third week were significantly (p< 0.05) lower. There was no significant

difference in MM between shaded and unshaded group of rams.

4.3.1.3.3 Sperm individual motility (IM)


sperm IM. The sperm IM value obtained for the shaded rams was significantly

(p<0.05) higher in week 3 compared to values obtained for week 1 and 2. In the

unshaded rams the sperm IM was significantly (p< 0.05) lower in week 2 and 3

compared to week 1 . However, the sperm IM was significantly(p < 0.05) lower in

unshaded rams in weeks 2 and 3 compared to the respective values of the shaded

group.

4.3.1.3.4 Sperm cell concentration

Table 4.17 shows the results of the effect of exposure to solar radiation on

sperm cell concentration. The shaded group revealed insignificant increase in sperm

cell concentration during the experimental period. The unshaded group of rams

showed significantly (p< 0.05) lower values of sperm cell concentration in the

second and third week compared to the first week. The unshaded group of rams had

significantly (p<0.05) higher sperm cell concentration in the first week of the

experimental period compared to the value obtained for the shaded group .

4.3.1.3.5 Incidence of live sperm


incidence of living spermatozoa (%). In the shaded group of rams, there was no

significant change in the incidence of living sperm

Table 4.16 Effect of exposure to solar radiation on sperm individual motility, IM

(%) in Desert rams.

( n =12 , mean± S.E.M.).

Time


1

B65.06 a

A65.01 a NS

± 11.9 ± 6.45

2 B60.15 a

± 7.07

B43.75 b

± 15.99 *

3 A76.25 a

± 3.75

AB55.10 b

± 6.45 *

SL * *








Table 4.17 Effect of exposure to solar radiation on sperm cell concentration

(x109/ml) in Desert rams.

(n = 12, mean± S.E.M.).

Time


1

A1.84 b

± 0.22

A3.59 a

± 0.82

*

2

A2.18 a

± 0.23

B1.48 a

± 0.25 NS

3

A2.85 a

± 0.85

B1.93 a

± 0.42 NS

SL NS *








Table 4.18 Effect of exposure to solar radiation on the incidence of live sperm

(%) in Desert rams.

(n = 12, mean± S.E.M.)

Time


1

A99.15 a

± 0.32

B91.23 b

± 2.97

*

2 A95.30 a

± 3.02

A98.63 a

± 0.48 NS

3 A98.18 a

± 1.41

A97.78 a

± 0.43 NS

SL NS *








during the experimental period. In the unshaded group of rams, the incidence of

living sperms was significantly (p<0.05) higher in the second and third week

compared to the first week.The percent of live sperms was significantly (p<0.05)

lower in unshaded rams only in the first week compared to the value reported for the

shaded rams.

4.3.1.3.6 Incidence of abnormal sperm


incidence of abnormal spermatozoa (%). In the shaded and unshaded group of rams,

the percentage of abnormal spermatozoa was significantly (p<0.5) higher in the

second and third week of the experimental period compared to the first week.The

abnormal sperms percentage was significantly higher in the unshaded group of rams

in the first, second and third week (p< 0.05, p< 0.01, p< 0.001) compared to the

respective shaded group values.

4.3.1.3.7 Semen pH

Table 4.20 shows the results of the effect of exposure to solar radiation on

semen pH. . In both groups of rams, semen pH was lower in the second week of the

experimental period and the change reported for the shaded rams was significant

(p<0.05). There was no significant difference in semen pH values obtained for the

shaded and unshaded group of rams.

4.3.1.4 Scrotal circumference (SC)

Table 4.21 shows the results of the effect of exposure to solar radiation on SC.

Both groups of rams showed a gradual decrease in SC during the experimental period.

Exposure of rams to solar radiation did not

Table 4.19 Effect of exposure to solar radiation on the incidence of abnormal

sperm (%) in Desert rams.

(n =12 mean,± S.E.M.).

Time


1

B1.38 b

± 0.38

B9.65 a

± 5.11

*

2

A4.83b

± 2.81

A22.10 a

± 11.25 **

3

A3.55 b

± 2.16

A39.63 a

± 16.78 ***

SL * *





Table 4.20 Effect of exposure to solar radiation on semen pH in Desert rams.

(n = 12 , mean± S.E.M.).

Time


1

A7.30 b

± 0.03

A7.25 a

± 0.14

NS

2 B6.88 a

± 0.13

A6.95 a

± 0.05 NS

3 A7.38 a

± 0.13

A7.13 a

± 0.13 NS

SL * NS






* : Significant at P < 0.05.


Table 4.21 Effect of exposure to solar radiation on scrotal circumference (cm)

in Desert rams.

(n = 12,mean± S.E.M.).

Time


1

A30.10 a

± 0.68

A31.88 a

± 0.72

NS

2 A29.75 a A31.13 a NS

± 1.09 ± 0.47

3 A28.88 a

± 0.83

A29.88 a

± 0.66 NS

SL NS NS





affect the SC measurements significantly; however, the values were slightly higher in

unshaded rams.

4.3.2 Effects of exposure to solar radiation and exhaustion test


4.3.2.1.1 Packed cell volume (PCV)

Table 4.22 shows the results of the effect of exhaustion test on the PCV level

of the shaded group of rams . There was no significant change in PCV level for pre-

or post-exhaustion values during the experimental period. However, the results

indicate that the post-exhaustion values of PCV level were significantly (p< 0.05)

lower during the three days of the test.

Table 4-23 shows the results of the effect of exhaustion test on the PCV level

of the unshaded group of rams. There was no significant change in the pre- exhaustion

or post-exhaustion values of PCV during the experimental period. However, the post-

exhaustion PCV level was significantly (p<0.05) lower in day 3 compared to the pre-

exhaustion value.

4.3. 2.1.2 Leukocytic indices

Table 4.24 shows the results of the effect of exhaustion test on total leukocyte

count (TLC) of the shaded group of rams. The pre-exhaustion value was

significantly(p< 0.05) higher in day 2 . The exhaustion test decreased significantly

(p< 0.05) the TLC in the first and second day compared to the third day.

Table 4-25 shows the results of the effect of exhaustion test on TLC of the

unshaded group of rams. For post-exhaustion value , a significantly (p<0.05) lower

value was obtained in the third day.

Table 4.22 Effect of exhaustion test on PCV (%) in shaded Desert rams.

(n = 24 , mean± .S.E.M.).

Time

(Days) Before exhaustion After exhaustion SL

1

A 34.33 a

± 1.86

A 27.67 b

± 1.76

*

2 A 35.50 a

± 1.89

A 31.25 b

± 2.66 *

3 A 34.33 a

± 2.03

A 29.33 b

± 3.33 *

SL NS NS








Table 4.23 Effects of exhaustion test on PCV (%) in unshaded Desert rams.

(n = 18 , mean± S.E.M.).

Time


1

A 31.25 a

± 1.75

A 28.25 a

± 2.46

NS

2 A 32.15 a A 28.67 a NS

± 3.10 ± 2.67a

3 A 30.50 a

± 1.71

A 26.13 b

± 0.71 *

SL NS NS








Table 4.24 Effect of exhaustion test on total leukocyte count, TLC (×103/µl)

in shaded Desert rams.

( n = 24, mean ± S.E.M.).

Time


1

B 6.28 a

± 1.51

B3.98 b

± 0.57

*

2 A 8.46 a

± 0.24

AB 4.14 b

± 0.44 *

3 B 4.50 a

± 0.26

A 5.36 a

± 0.23 NS

SL * *








Table 4.25 Effect of exhaustion test on total leukocytes count, TLC (× 103/µl)

in unshaded Desert rams.

( n = 18 , mean± S.E. M.) .

Time


1

A 6.88 a

± 0.98

AB 5.75 b

± 1.35

*

2 A 6.98 a

± 0.82

A 7.68 a

± 1.60 NS

3 A 5.78 a

± 0.86

B 4.85 a

± 1.45 NS

SL NS *








Compared to the pre-exhaustion value, the exhaustion test reduced significantly

(p<0.05) the TLC only in day 1.

Table 4.26 shows the results of the effect of exhaustion test on differential

leukocyte count (DLC) of the shaded group of rams. There was a progressive decrease

in the ratio of lymphocytes for pre- and post- exhaustion values, but this change was

not significant. However, compared to the pre-exhaustion values, the post-exhaustion

ratio of lymphocytes was slightly higher in the first and third day.

The exhaustion test slightly increased the pre- and post- exhaustion values of

neutrophils in the shaded group of rams. However, compared to the pre-exhaustion

values, the exhaustion test slightly decreased the ratio of neutrophils during the

experimental period.

The exhaustion test resulted in a slight increase in the value of eosinophils in

the shaded group in days 2 and 3. In the post-exhaustion state, lower values of

eosinophils were obtained compared to the pre-exhaustion values.

For post–exhaustion values of monocytes, there was a significant (p< 0.05)

increase in days 2 and 3. The exhaustion test increased the ratio of monocytes in days

2 and 3.

Table 4-27 shows the results of the effect of exhaustion test on differential

leukocytes count (DLC) of unshaded rams. The exhaustion test slightly reduced the

ratio of lymphocytes in the third day of the experimental period. The exhaustion test

slightly increased the ratio of lymphocytes compared to the respective values obtained

before exhaustion

The pre- and post-exhaustion values of neutrophils were slightly lower in the

second day. Compared to the pre-exhaustion state, exhaustion

Table 4.26 Effect of exhaustion test on differential leukocyte count, DLC

(%) in shaded Desert rams.

(n = 24, ± mean S.E.M.).

Cell type

(%) Time

(Days)

Before exhaustion

After exhaustion

SL

1

A 58.75 a

± 1.65

A 62.50 a

± 1.04

NS

2 A 58.25 a

± 2.59

A 57.25 a

± 1.97 NS

3 A 53.00 a

± 5.61

A 55.50 a

± 2.40 NS

Lymphocytes

SL NS NS

1 A 31.25 a

± 1.31

A 30.50 a

± 1.32 NS

2 A 34.00 a

± 1.96

A 31.25 a

± 1.25 NS

3 A 37.00 a

± 6.22

A 32.00 a ± 2.38

NS

Neutrophils

SL NS NS

1 A 4.22 a

± 2.02

A 2.25 a

± 0.25 NS

2 A 3.75 a

± 1.03

A 3.00 a

± 0.91 NS

3 A 4.25 a

± 1.11

A 3.00 b

± 0.71 NS

Eosinophils

SL NS NS

1 A 5.75 a

± 0.75

B 4.76 a

± 0.25 NS

Monocytes

2 A 4.11 a

± 0.41

A 8.50 a

± 2.33 NS

3 A 5.75 a

± 1.11

A 9.25 a

± 2.17 NS

SL NS *


significantly different .





NS.:Not significant.

Table 4.27 Effect of exhaustion test on differential leukocyte count, DLC

(%), in unshaded Desert rams

(n = 18 , mean± S.E.M).

Cell type

(%)

Time

(Days)

Before

exhaustion

After

exhaustion SL

1

A 46.67 a

± 3.84

A 50.67 a

± 6.36

NS

2 A 51.67 a

± 7.53

A 51.67 a

± 2.48 NS

3 A 52.67 a

± 8.83

A 48.00 a

± 10.97 NS

Lymphocytes

SL NS NS

1 A 46.67 a

± 4.26

A 43.33 a

± 6.17 NS

2 A 40.67 a

± 8.84

A 38.33 a

± 3.53 NS

3 A 43.33 a

± 10.87

A 47.00 a

± 11.63 NS

Neutrophils

SL NS NS

1 A 1.67 a

± 0.67

A 1.33 a

± 0.33 NS

2 A 2.33 a

± 0.33

A 3.83 a

± 0.33 NS

3 A 0.67 a

± 0.67

A 3.00 a

± 0.05 NS

Eosinophils

SL NS NS

1 A 3.67 a

± 0.88

A 4.67 a

± 1.76 NS

2 A 5.33 a

± 1.20

A 8.67 a

± 0.88 NS

3 A 3.67 a

± 1.45

A 4.00 a

± 0.01 NS

Monocytes

SL NS NS




NS. Not significant

test slightly lowered the ratio of neutrophils , except in the third day where the post-

exhaustion ratio of neutrophils was higher.

For pre- and post-exhaustion values of eosinophils, higher values were

obtained in the second day. Post- exhaustion, the eosinophils ratio increased slightly

in the last two days compared to the respective pre-exhaustion values.

The exhaustion test slightly increased the pre- and post-exhaustion ratio of

monocytes in the second day only. Compared to pre-exhaustion state, the exhaustion

test slightly increased the ratio of monocytes.


Table 4-28 shows the results of the effect of exhaustion test on serum total

protein concentration in shaded group of rams. The pre- exhaustion values of total

protein did not reveal a consistent pattern, but the post- exhaustion values showed

progressive decrease. For both pre- and post- exhaustion values there was a

significant reduction (p< 0.05) in the third day. The exhaustion test induced a

significant (p<0.05) decrease in serum total protein level in the second and third day

compared to the pre-exhaustion values.

Table 4-29 shows the results of the effect of exhaustion test on serum total

protein concentration of unshaded rams .For both pre- exhaustion and post-

exhaustion values, there was no significant change during the experimental period.

However, compared to the pre-exhaustion state, the post – exhaustion serum protein

levels were significantly (p< 0.05) lower in the first and second day.

4.3.2.1.4 Serum albumin

Table 4.30 shows the results of the effect of exhaustion test on serum albumin

concentration of shaded group of rams. The exhaustion test

Table 4.28 Effects of exhaustion test on serum total protein concentration (g/dl)


(n = 24 ,mean± S.E.M.).

Time


1

A 7.63 a

± 0.35

A 7.68 a

± 0.33

NS

2

A 7.88 a

± 0.29

A 7.35 b

± 0.32

*

3

B 7.20 a

± 0.29

B 6.60 b

± 0.19

*

SL * *








Table 4.29 Effects of exhaustion test on serum total protein concentration (g/dl)


(n = 18 , mean± S.E.M.) .

Time


1

A 7.73 a

A 7.13 b

*

± 0.43 ± 0.63

2 A 7.77 a

± 0.03

A 6.93 b

± 0.33

*

3 A 7.33 a

± 0.29

A 6.77 a

± 0.24

NS

SL NS NS







NS:Not significant.

Table 4.30 Effect of exhaustion test on serum albumin concentration (g/dl)


(n = 24 , mean± S.E.M).

Time


1 A 3.50 a

± 0.12

A 3.65 a

± 0.05

NS

2 A 3.65 a

± 0.12

A 3.65 a

± 0.16

NS

3 A 3.38 a

± 3.75

A 3.75 a

± 0.21

NS

SL NS NS





slightly increased the serum albumin level in day 3. The results indicate that

generally, the post – exhaustion serum albumin levels were slightly higher compared

to the respective pre-exhaustion values.

Table 4-31 shows the results of the effect of exhaustion test on serum albumin

concentration of unshaded rams. There was no significant difference in pre-

exhaustion and post-exhaustion values during the experimental period.


Table 4.32 shows the results of the effect of exhaustion test on serum urea

concentration of the shaded group of rams. There was a significant increase in urea

level for both pre-exhaustion (p<0.05) and post-exhaustion (p<0.01) values. The

exhaustion test increased the serum urea level significantly (p<0.05) in the third day

of experimental period.

Table 4-33 shows the effect of exhaustion test on serum urea concentration of

the unshaded group of rams. The exhaustion test decreased the serum urea level

slightly in days 2 and 3. There was no significant difference in pre-exhaustion and

post-exhaustion urea levels during the experimental period.


Table 4.34 shows the results of the effect of exhaustion test on plasma glucose

concentration in the shaded group of rams. The plasma glucose level increased

significantly (p<0.05) during the experimental period for both per-exhaustion and

post-exhaustion values. Compared to the pre-exhaustion values, the exhaustion test

increased the plasma glucose level significantly (p<0.05) in days 1 and 3.

Table 4.31 Effect of exhaustion test on serum albumin concentration (g/dl)


(n = 18 , mean± S.E.M.).

Time


1

A 3.70 a

A 3.77 a

NS

± 0.06 ± 0.22

2 A 3.67 a

± 0.17

A 3.47 a

± 0.13

NS

3 A 3.40 a

± 0.12

A 3.63 a

± 0.18

NS

SL NS NS




NS. Not significant.

Table 4.32 Effect of exhaustion test on serum urea concentration (mg/dl)


(n = 24 , mean± S.E.M).

Time


1

B 17.45 a

± 2.85

B 17.20 a

± 3.20

NS

2 B 18.38 a

± 3.17

A 21.75 a

± 2.29a

NS

3 A 21.08 b

± 3.48

A 28.40 a

± 0.16a

*

SL * **






* : Significant at p< 0.05.

** : Significant at p < 0.01.


Table 4.33 Effect of exhaustion test on serum urea concentration (mg/dl)


(n = 18, mean ± S.E.M.).

Time


1

17.67 a

A 17.10 a

NS

± 0.63 ± 1.78

2 A 16.80 a

± 4.18

A 14.43 a

± 1.79

NS

3 A 18.93 a

± 2.58

A 15.57 a

± 1.85

NS

SL NS NS





Table 4.34 Effect of exhaustion test on plasma glucose concentration (mg/dl)


(n = 24 , mean± S.E.M.) .

Time

(Days)

Before exhaustion After exhaustion SL

1

B 51.03 b

± 5.26

B 58.40 a

± 2.28

*

2 A 54.88 a

± 0.75a

B 58.50 a

± 4.30

NS

3 A 57.05 b

± 3.02

A 62.23 a

± 4.51

*

SL * *







NS: Not significant

Table 4-35 shows the results of the effect of exhaustion test on plasma glucose

levels of unshaded rams .For post-exhaustion values , the glucose level was

significantly (p<0.05) higher in day 2. The exhaustion test increased the glucose

level significantly (p<0.05) for the three days of the experimental period.



Table 4.36 shows the results of the effect of exhaustion test on ejaculate

volume in the shaded group of rams. For both the first and last sample collections,

there was progressive decrease in ejaculate volume during the experimental period

and the reduction was significant (p<0.05) in the last day of the first collection. The

ejaculate volume was significantly (p< 0.05) reduced by exhaustion in the three days

of the test.

Table 4.37 shows the results of the effect exhaustion test on ejaculate volume

in the unshaded group of rams. The value of last collection obtained in the first day

was significantly (p< 0.05) lower compared to the values obtained subsequently.

There was no significant difference between the first and last ejaculate volumes.


Table 4.38 shows the results of the effect of exhaustion test on sperm MM in

the shaded group of rams. For the first collections, the exhaustion test progressively

reduced the MM, which did not attain the level of significance. However, the

reduction in MM observed for the last collections did not reveal a consistent pattern.

The exhaustion test slightly increased sperms MM in the first and third day, and it

reduced sperms MM in the second day.

Table 4.35 Effect of exhaustion test on plasma glucose concentration (mg/dl)

in unshaded Desert rams .

(n = 18 , mean± S.E.M.).

Time


1

A 50.93 b

± 9.45

B 66.43

± 5.86

*

2 A 54.00 b

± 5.12

A 71.87 a

± 6.62 *

3 A 50.00 b

± 3.41

B 67.13 a

± 7.71 *

SL NS *





SL: Significance level..



Table 4.36 Effects of exhaustion test on ejaculate volume (ml) of shaded Desert

rams.

(n = 54 , mean± S.E.M).

Sample collection Time

(Days) First Last SL

1

A1.50 a

± 0.20

A0.50 b

± 0.10

*

2 A1.28 a

± 0.19

A0.33 b

± 0.13 *

3 B0.87 a

± 0.09

A0.30 b

± 0.01 *

SL * NS







NS: Not significant

Table 4.37 Effects of exhaustion test on ejaculate volume (ml) of unshaded

Desert rams.

(n = 38 , mean± S.E.M.) .


(days) First Last SL

NS

1 A0.73 a

± 0.38

B0.60 a

± 0.23

2 A0.90 a

± 0.21

A1.05 a

± 0.75 NS

3 A0.75 a

± 0.15

A0.85 a

± 0.35 NS

SL NS *

Mean values within the same row bearing similar superscripts are not






NS:Not significant

Table 4.38 Effects of exhaustion test on sperm mass motility , MM (0-5)

of shaded Desert rams.

(n = 54 , mean± S.E.M) .



1

A3.25 a

± 0.25

A3.50 a

± 2.50

NS

2 A3.13 a

± 0.31

A2.00 a

± 0.58 NS

3 A2.67 a

± 0.33

A2.75 a

± 0.75 NS

SL NS NS




NS.:Not significant .

Table 4.39 shows the results of the effect of exhaustion test on sperm MM in

unshaded group of rams. The exhaustion test did not influence significantly the sperm

MM values in the first and last semen sample collections during the experimental

period. The MM showed a slight increase in the second and third day in response to

exhaustion test.


Table 4.40 shows the results of the effect of exhaustion test on the sperms IM

of the shaded group of rams. The exhaustion test significantly (p<0.05) lowered the

sperm IM in the last two days for the first collection. For the values of the last

collections, the sperm IM was significantly (p< 0.05) lower in the third day compared

to values obtained in days I and 2. However, the exhaustion test significantly (p<0.05)

reduced IM in the first and third day of sampling.

. Table 3.41 shows the results of the effect of exhaustion test on the sperms IM of

unshaded rams. For the initial collections of semen sample, the value was

significantly (p< 0.05) lower in day I; for the last collection values, the IM was

significantly (p< 0.05) lower in day 3. The exhaustion test significantly (p< 0.05)

increased IM in the first day and it decreased the value significantly(p<0.05) in the

third day of the experimental period.


Table 4.42 shows the results of the effect of exhaustion test on sperm cell

concentration of shaded rams. For the initial collections of semen samples during the

test, there was a progressive significant (p< 0.05) decrease in sperm cell

concentration.The last collection values indicate that the sperm cell concentration was

significantly (p<0.05) lower in days 2 and 3 compared to day 1 value. The exhaustion

test significantly (p<0.05) reduced sperm cell concentration in the first and second

day.

Table 4.39 Effect of exhaustion test on sperm mass motility, MM (0-5) of

unshaded Desert rams.

(n = 38 , mean± S.E.M).



1

A2.67 a

± 0.88

A2.50 a

± 0.12

NS

2 A2.67 a

± 0.33

A3.75 a

± 0.13 NS

3 A2.50 a

± 0.50

A2.75 a

± 0.75 NS

SL NS NS


not significantly different



Table 4.40 Effect of exhaustion test on sperm individual motility, IM (%)


(n = 54 , mean± S.E.M).



1

A57.50 a

± 10.31

A42.50 b

± 2.50

*

2 B37.50 a

± 4.33

A35.00 a

± 5.00 NS

3 B33.33 a

± 12.02a

B16.67 b

± 11.67 *

SL * *





SL: Significance level .

* : Significant at P< 0.05.


Table 4.41 Effect of exhaustion test on sperm individual motility, IM (%)

of unshaded Desert rams

(n = 38 ,mean± S.E.M.) .

Sample collection Period


1

B13.33 b

± 4.41

A30.30 a

± 3.10

*

2 A36.67 a

± 8.82

A35.00 a

± 15.00 NS

3 A30.00 a

± 10.00

B22.50 b

± 7.50 *

SL * *







NS:Not significant

Table 4.42 Effect of exhaustion test on sperm cell concentration (x109/ml)


(n = 54 ,mean± S.E.M.).



1 A2.33 a

± 0.30

A1.31 b

± 0.24 *

2 B1.42 a

± 0.28

B0.61 b

±0. 70 *

3 B1.07 a

± 0.46

B0.98 a

± 0.15 NS

SL * *







NS: Not significant

Table 4.43 shows the results of the effect of exhaustion test on sperm cell

concentration of unshaded rams. The initial collection values of sperm cell

concentration were significantly (p< 0.05) lower in days 2 and 3. However, for last

sample collections, the sperm cell concentration was significantly (p< 0.05) higher in

day 3. The exhaustion test was associated with a significant (p<0.01) decrease in

sperm cell concentration in day 1; in day 3, the test caused a significant (p<0.05)

increase.


Table 4.44 shows the results of the effect of exhaustion test on live sperm

incidence of shaded rams. The exhaustion test did not influence significantly the

incidence of live sperms.

Table 4.45 shows the results of the effect of exhaustion test on live sperm

incidence of unshaded rams.For the initial semen sample collections, the live sperm

percent was significantly (p< 0.05) lower in the third day of experimental period.The

exhaustion test significantly (p<0.05) increased the live sperms incidence in the third

day of the experimental period


Table 4.46 shows the results of the effect of exhaustion test on the

incidence of abnormal sperms of shaded group of rams. For the initial semen sample

collections, the abnormal sperm percent was significantly (p<0.05) lower in days 2

and 3. The last collection values indicate that the abnormal sperm percent was

significantly (p<0.05) higher in day 2 compared to values obtained in days 1 and 3.

The exhaustion test reduced the abnormal sperms percent in days 1 and 3 and it

produced a significant (p < 0.05) increase in day 2.

Table 4.43 Effects of exhaustion test on sperm cell concentration (x106 /ml)

of unshaded Desert rams.

(n = 38, mean± S.E.M).



1

A1.92 a

B0.41 b **

± 0.94 ± 0.01

2 B0.46 a

± 0.25

B0.39 a

± 0.18 NS

3 B0.64 b

± 0.10

A1.04 a

± 0.45 *

SL ** *






** : Significant at p<0.01.



Table 4.44 Effects of exhaustion test on the incidence of live sperm (%)


(n = 54 ,mean± S.E.M.).


(Day) First Last SL

1

A98.53 a

± 1.01

A99.65 a

± 0.35

NS

2 A98.88 a

± 0.54

A98.63 a

± 0.81 NS

3 A99.47 a

± 0.29

A97.30 a

± 0.10 NS

SL NS NS




NS: Not significant

Table 4.45 Effect of exhaustion test on the incidence of live sperm (%)


(n = 38, mean± S.E.M).



1

A98.57 a

± 0.73

A99.50 b

± 1.10

NS

2 A99.23 a

± 0.43

A98.30 a

± 0.10 NS

3 B95.95 b

± 0.95

A99.25 a

± 0.25 *

SL * NS







NS: Not significant

Table 4.46 Effect of exhaustion test on the incidence of abnormal sperm (%)


(n = 54,mean ± S.E.M.).



1

A4.65 a

± 3.23

B2.30 a

± 1.30

NS

2

B1.35 b

± 0.16

A4.97 a

± 2.95 *

3

B2.37 a

± 0.29

B2.05 a

± 1.15 NS

SL * *







NS: Not significant

Table 4.47 shows the results of the effects of exhaustion test on the incidence of

abnormal sperms of unshaded rams. For the initial semen sample collections, the

abnormal sperm percent decreased significantly (p<0.05) in days 2 and 3. For the last

collection of semen samples, the abnormal sperms percent was significantly (p<0.05)

lower in day 3.There was a significant (p< 0.05) reduction in abnormal sperm percent

in days I and 3 in response to exhaustion test, and a significant (p<0.05) increase in

abnormal sperm percent in day 2.

4.3.2.2.7 Semen pH

Table 4.48 shows the results of the effect of exhaustion test on semen pH of

the shaded rams . For the initial semen sample collections, the pH was significantly

(p<0.05) higher in days 2 and 3 compared to day 1 value. For last collections, the pH

value was slightly lower in day 3 compared to the values obtained in days 1 and 2.

The exhaustion test did not affect the pH values significantly. However, the general

pattern indicates that the last collection value was higher in days 1 and 2 and it was

lower in day 3.

Table 4.49 shows the results of the effects of exhaustion test on semen pH in

unshaded group of rams. The values obtained did not reveal a consistent pattern

related to the experimental treatments

Table 4.47 Effect of exhaustion test on the incidence of abnormal sperm (%)


(n = 38 , mean± S.E.M.).



1

A21.57 a

± 14.39

A12.50 b

± 0.20

*

2 B4.70 b

± 2.83

A8.40 a

± 7.50 *

3 B5.15 a

± 1.05

B2.90 b

± 0.50 *

SL * *







Table 4.48 Effect of exhaustion test on semen pH in shaded Desert rams.

(n = 38 ,mean± S.E.M.).



1

B7.08 a

± 0.08

A8.00 a

± 0.00

NS

2 A7.88 a

± 0.13

A8.00 a

± 0.01 NS

3 A7.83 a

± 0.12

A7.75 a

± 0.25 NS

SL * NS



Table 4.49 Effect of exhaustion test on semen pH in unshaded Desert rams.

(n = 38, mean± S.E.M.).



1

A7.67 a

± 0.44

A7.80 a

± 0.14

NS

2 A7.83 a

± 0.17

A7.75 a

± 0.25a NS

3 A8.00 a

± 0.1

A8.00

± 0.01a NS

SL NS NS





4.4. Discussion

In this experiment, the effects of chronic exposure of mature Desert

rams to direct solar radiation on thermoregulation, blood composition and

semen characteristics were investigated. The combined effects of

exposure to solar radiation and frequent ejaculation on blood composition

and semen characteristics were also evaluated.

The experiment was performed during wet summer conditions

(October and November), where the impact of thermal environment is

moderate and there is marked diurnal changes in ambient temperature

(16.25ºC) compared to mean values usually recorded during dry summer

conditions. Exposure of the treated group of Desert rams to solar

radiation induced a marked influence on the indices of thermoregulation

(Tr and RR), particularly the values obtained in the afternoon , but the

rams were able to readjust their thermoregulation. There were indications

that the measured blood metabolites and seminal traits of Desert rams

were influenced by exposure to direct solar radiation. The data obtained

also indicate that frequent ejaculation influenced certain blood

constituents and semen characteristics irrespective of thermal

environment.

4.4.1. Exposure to solar radiation

4.4.1.1. Thermoregualtion

In the present study, the mean value of rectal temperature (Tr) of

unshaded rams measured at 7:00 a.m. was significantly higher in the

second week of the experimental period compared to values obtained in

the first and third week (Table 4.3). This response is closely related to the

prevailing high ambient temperature. However, the significantly higher

Tr values measured at 2: 00 p.m in the first week of exposure to solar

radiation compared to value obtained subsequently, and the value of the

Tr obtained for the unshaded rams (Table 4.4) are clearly attributed to an

increase in the rate of heat gain from solar radiation which exceeded the

rate of heat loss. Consequently, heat storage induced an increase in body

temperature of rams. The present findings are consistent with

observations of Abdelatif and Ahmed (1992) who reported that exposure

of Desert rams to solar radiation during wet summer was associated with

an increase in Tr, particularly in the afternoon. Gupta and Acharya (1987)

reported higher Tr values in the afternoon in Chokla and Nali rams when

exposed to solar radiation for 8 hrs during extreme tropical summer

conditions. Similarly exposure of Barki rams and their cross Merino

(Azamel et al., 1987) and Corriedale wethers (Razzaque and Ibnoof,

1990) to direct solar radiation increased Tr, particularly in the afternoon.

The higher Tr values reported in Desert rams in the first week of

exposure to solar radiation and subsequent lowering indicates that Desert

rams are able to readjust metabolic rate by reduction of food intake and

enhancement of heat dissipation.

The current results indicated that the respiration rate (RR) values

obtained at 7: 00 a.m. were significantly higher in both groups of rams in

the second week of the experimental period (Table 4.5). This response

coincides with the prevailing maximum ambient temperature and Tr

values reported at 7: 00 a.m. However, the significantly higher RR values

obtained for unshaded rams compared to shaded group is attributed to the

influence of solar heat load and the need for enhancement of evaporative

heat dissipation from the respiratory tract. Turnpenny et al. (2000)

indicated that in sheep, thermal balance is achieved by panting. High

values of RR were reported in the afternoon on exposure of Desert rams

(Abdelatif and Ahmed, 1992), Barki rams and their cross, Merino

(Azamel et al., 1987) and Corriedale wethers (Razzaque and Ibnoof,

1990) to solar radiation. A similar marked increase of RR in the afternoon

was observed in unshaded Barki (Hassanian et al., 1996) and Merino

(Cloete et al., 2000) rams. The findings indicate that the Desert rams

were stressed by exposure to solar radiation. The changes in Tr and RR

indicate that the indices of thermoregulation were influenced by heat

stress.

4.4.1.2. Blood composition

The results indicate that exposure of Desert rams to solar radiation

was associated with changes in the blood parameters investigated. The

lower PCV noted in unshaded rams (Table 4.7) could be attributed to the

recognized heat induced increase in water consumption and consequently

occurrence of hypervolaemic haemodilution. The low values of PCV

previously reported on exposure of Barki rams (Hassanian et al., 1996)

and Merino ewes (Cloete et al., 2000) to solar radiation were attributed to

increased water consumption and haemodilution. However, Abdelatif and

Ahmed (1992) reported that exposure of Desert rams to solar radiation

did not influence significantly the PCV level. The low value of PCV

could also be partially attributed to low food intake and low metabolic

rate.

Habeeb et al. (1992) reported low values of PCV level in studies

on heat stressed animals and attributed this to haemodilution and

reduction in cellular oxygen requirements to minimize internal metabolic

heat production. The reduction in PCV level reported in heat stressed

rams in the present study could also be associated with endocrine

responses which retained water in intravascular compartment. In heat

stressed Lettle wethers (Guerrini and Bertchinger, 1983) and castrated

Merino rams (Parrott et al., 1988), low values of PCV were associated

with high blood level of the antidiuretic hormone vasopressin.

In the present study, both shaded and unshaded rams maintained

progressively higher total leukocyte count (TLC) during the experimental

period (Table 4.8). This increase could be associated with modulation in

the responses of the rams to thermal stress. Exposure to heat stress

stimulates the release of glucocorticoids which usually increase the

leukocytes in blood from lymphoid tissue and bone marrow (Swenson,

1993).

Bland et al. (2000) noted that adrenal steroids are essential for

homeostasis and survival during severe physiological stress. The authors

also reported that in mice, activation of ACTH receptors in the adrenal

gland, glucocorticoid act on immune tissues.

In the present study, different types of leukocytes responded

differently to the exposure of Desert rams to solar radiation (Table

4.9).The lower ratio of lymphocytes reported in the first and second

weeks of exposure to solar radiation could be related to the effects of

glucocorticoids. Ganong (2003) noted that glucocorticoids decrease the

number of lymphocytes and the size of lymph nodes and thymus by

inhibiting lymphocytes, mitotic activity and increasing destruction of

lymphocytes. The low ratio of lymphocytes observed during acute

exposure of rams to solar radiation could also be accounted for by heat –

induced lymphocytes death and removal of these cells physiologically

without inducing inflammatory responses (apoptosis) (Waheed et al.,

2002).

The significantly higher ratio of neutrophils observed in the

unshaded rams during the first week of exposure to solar radiation could

be associated with high levels of cortisol secreted during acute heat stress.

Sevi et al. (2001) reported higher number of neutrophils in Tasmania

ewes during exposure to solar radiation. The authors attributed this

response to the increased concentration of ACTH which stimulates the

production of cortisol from adrenal cortex. The remarkable eosinopenia

observed in unshaded rams in the third week of the experimental period

compared to the shaded rams values could be associated with increases in

the levels of adrenocorticoids which decrease the number of eosinophils

by increasing their sequestration in the spleen and lungs (Swenson, 1993;

Ganong, 2003). In the second and third week of exposure of rams to solar

radiation, there was a significant increase in the ratio of monocytes

compared to values obtained in the first week. This response could be

accounted for by the inhibition of migration of monocytes from spleen

and bone marrow and reduction in their circulating number in response to

short-term rise of blood cortisol. The general effect of cortisol usually

subsides during chronic heat stress and adaptation to hot environment

(Hammond et al., 1996).

In the current results, the shaded rams had significantly lower

serum total protein level in the third week of experimental period (Table

4.10). This could be related to an increase in water intake by rams

stimulated by the prevailing high ambient temperature. The lower values

of serum total protein could also be attributed to low food intake and

haemodilution.

In heat stressed Egyptian Suffolk rams, Marai et al. (2003)

reported low serum protein levels; this was attributed to increase in water

intake associated with decrease in food intake. However, the significantly

higher total protein level reported in rams exposed to solar radiation in

the third week compared to the control could be attributed to increase in

metabolism and reduction in the amount of energy retained. Beede and

Collier (1986) indicated that the general increase in metabolism in

ruminants during heat stress is mainly accounted for by tissue protein

catabolism. The increase in serum protein could also be attributed to

increased urinary nitrogen retention in response to low food intake.

Guerrini et al. (1982) reported that exposure of Lettle wethers to

experimental heat stress increased plasma protein level. The authors

attributed this response to increased nitrogen retention. However, in

Desert rams fed lucerne hay and exposed to direct solar radiation, the

plasma total protein level increased insignificantly (Abdelatif and

Ahmed, 1992).

In the current results the concentration of serum albumin was

significantly lower in the second week of exposure to solar radiation. This

response is clearly associated with high ambient temperature and

increased cortisol level, as the blood albumin concentration is inversely

related to blood cortisol level. Leonard and McMillan (1964) reported

that the decrease in the binding capacity of albumin in blood was

associated with high free blood cortisol level. However, the significantly

lower albumin level observed in the second week of the experimental

period in the unshaded rams could be related to the depressive effects of

thermostatic signals on voluntary food intake in sheep. The decline in

food intake resulted in lowering of the amount of amino acids available

for albumin synthesis in the liver (Payne and Payne, 1987). Abdelatif and

Ahmed (1992) reported that exposure of Desert rams fed lucerne hay to

solar radiation did not influence the plasma albumin concentration.

The results indicate that the serum urea concentration declined in

the third week of the experimental period in both groups of rams (Table

4.12). This could be associated with decrease in food intake. Payne and

Payne (1987) indicated that lowering the amount of protein required for

formation of NH3 which is converted to urea in the liver, is usually

responsible for decrease in blood urea concentration. However, the

general pattern indicates that during the experimental period, the serum

urea concentration was slightly lower in unshaded rams compared to

values obtained for the shaded rams, which is attributed to higher rate of

water consumption and depressive effect of thermal load on food intake.

Also the low values of serum urea could be accounted for by increased

secretion of catabolic hormones of the adrenal cortex in heat stressed

rams. Kamal and Shebaita (1972) reported that in ruminants exposed to

heat stress with low dietary protein, the secretion of the catabolic

hormones of the adrenal cortex is elevated , which results in nitrogen

losses and the nitrogen balance becomes negative. The present finding

regarding low serum urea level contradicts the results reported by

Abdelatif and Ahmed (1992) in Desert rams exposed to solar radiation.

In the current results, the slightly high plasma glucose

concentration observed in the first two weeks of the experimental period

in both groups (Table 4.13) could be related to stimulation of secretion of

glucocorticoids provoked by high ambient temperature. During heat

stress, the increase in the concentration of glucocorticoids increases

gluconeogenesis and hepatic glucogenesis (Kotby and Johnson, 1967).

The increase in plasma glucose could be attributed mainly to decrease in

metabolic activities associated with depressed peripheral glucose

utilization (Abdalla et al ., 1989). Kamal et al. (1970) noted that in

ruminants, heat stress induced inhibition of pancreatic B-cell activity and

consequent reduction of insulin secretion. Hassanain et al. (1996)

reported an increase in blood glucose level in Barki rams exposed to solar

radiation. The significantly lower plasma glucose level reported in both

groups in the third week of the experimental period and in the unshaded

rams compared to the control, could be related to low food intake in the

radiant environment and to decline of glucocorticoids secretion in

response to prolonged stress. A decrease in plasma glucose level of

Egyptian Suffolk rams in response to chronic heat stress was attributed to

low cortisol level (Marai et al., 2003).

4.4.1.3. Semen characteristics

The current results indicate that exposure of Desert rams to solar

radiation induced marked changes in seminal traits.

The ejaculate volume showed fluctuations in the shaded rams

during the experimental period, with significantly higher values obtained

in the second and third week (Table 4.14). This pattern could be

attributed to changes in the impact of the general thermal influence of the

prevailing ambient temperature (Table 4.2). However, in the group of

rams exposed to solar radiation, the ejaculate volume was progressively

reduced, particularly in the third week of the experimental period, and in

the second week compared to the value obtained for the shaded rams.

This response could be attributed to thermal stress and inhibition of the

role of the hypothalamus by reduction of prolactin hormone secretion.

Beede and Collier (1986) reported reduction of prolactin secretion, which

is necessary for the action of luteinizing hormone (LH) on leydig cells, in

response to thermal stress. The decline in ejaculate volume in rams

exposed to solar radiation could also be attributed to reduction in rete

testis fluid and its contents of androstene, progesterone and pregnenolone

(hormones considered as intermediates in biosynthesis of testosterone); a

reduction in their levels may reduce the secretory function of the

androgen dependent accessory genital gland (Main and Waites, 1973).

The present findings are in agreement with previous studies regarding

seminal traits of Egyptian Suffolk rams (Marai et al., 2003) exposed to

high ambient temperature.

In the current results, the sperm mass motility (MM) showed an

inconsistent pattern of reduction in the shaded group of rams, particularly

in the third week of the experimental period (Table 4.15). This reduction

could be related to the effects of increase in scrotal temperature in

response to the high ambient temperature during the second week of the

experimental period (Table 4-2). The unshaded rams showed a

progressive reduction in MM, in the second and third week of the

experimental period. This could be attributed to the cumulative effects of

direct exposure to solar radiation and impairment of scrotal thermo-

regulation. Jainudeen and Hafez (2000) indicated that spermatogenesis

requires a temperature considerably lower than that of the interior of the

body. The testes are maintained at a temperature 4–8º C below body

temperature in rams (Kastelic et al., 1996). The spermatozoa acquire

motility during their transit through the epididymal duct, which must be

maintained under low ambient temperature (Kastelie et al., 2000). The

authors also indicated that an increase in testicular temperature increased

metabolism with concurrent need for excess oxygen to sustain aerobic

metabolism. However, Setchell (1978) reported that in rams, blood flow

changes little in response to increase in testicular temperature and

consequently hypoxia develops. A similar decline in sperm MM was

reported in Egyptian Suffolk rams exposed to heat stress during summer

conditions (Marai et al., 2003).

In the current results, the sperm individual motility (IM) decreased

in both unshaded and shaded rams during the experimental period (Table

4.16). In the shaded rams, the increase in sperm IM was consistent and it

was remarkable in the third week. This change coincided with elevation

of ambient temperature during wet summer conditions. However, the

consistent reduction in sperm IM observed in unshaded rams, particularly

in the second and third week of exposure to solar radiation, could be

attributed to the effects of high thermal load on the scrotum. Increasing

the temperature of the epididymis disturbs its normal absorptive and

secretory functions, and changes in the ions and proteins of cauda

epididymis in heated testes usually lower the progressive motility of

sperms (Kastelic et. al, 1997., 2000). The significantly lower sperm IM

noted in the last two weeks of the experimental period in the unshaded

rams compared with the control, indicates that in addition to the general

effects of high ambient temperature on sperm IM, thermal load on Desert

rams exerted an additional detrimental effect by increasing scrotal

temperature.

The reduction in sperm cell concentration in rams exposed to solar

radiation (Table 4.17) could be associated with damage in all stages of

spermatogenesis. The findings of Kastelic et al. (1996) indicated that

spermatocytes and meiotic prophase were damaged due to thermal effects

with consequent decrease in number of spermatozoa in the ejaculate.

Scrotal hypothermia is necessary for normal spermatogenesis (Partsch et

al., 2000). However, Setchell and Waites (1971) reported that the

secretion of testicular fluid which begins before spermatogenesis is fully

established and persists if the production of spermatozoa is temporarily

stopped by locally heating the testis. Some of the constituents of the

testicular fluid are probably important in the nutrition of spermatozoa and

other germinal cells; this may influence the Meitotic division of cells

(Setchell and Waites, 1971).

The current results indicate that exposure of Desert rams to solar

radiation was associated with decrease in the percentage of live

spermatozoa (Table 4.18) in the first week of the experimental period

compared with the values obtained for the last two weeks.The

significantly lower value obtained for the first week compared to the

shaded rams could be related to the effects of solar radiation on testicular

and epididymal tissues. Exposure to heat stress alters the function of the

scrotal thermoregulation mechanism, which reduces the temperature

gradient which is usually maintained at 4–8ºC in rams (Stanbenfeldt and

Edqvist, 1993). The reduction in live sperms percent could also be

attributed to impaired heat exchange in the countercurrent system

between the spermatic artery and veins (Kastelic et al., 1996).

The results obtained in the current study indicate that the

percentage of abnormal spermatozoa was significantly higher in the

second and third week of the experimental period in the unshaded rams

(Table 4.19). The abnormal forms of head and tail and coiled tail were

probably associated with metabolic and structural changes. Brooks (1973)

indicated that the low temperature maintained in the cauda epididymis

may contribute to the longevity of spermatozoa stored in this part of the

organ. Boundy (1993) indicated that in rams, primary spermatozoa

abnormalities (abnormal heads, detached heads) occurred in testis during

spermatogenesis while secondary spermatozoal abnormalities

(protoplasmic droplets) were found in the epididymal journey and tertiary

spermatozoal abnormalities (bent and cut tails) were related to technical

errors during handling of semen sample. In ruminants, during epididymal

transit, spermatozoa acquire certain selected proteins secreted by

epithelial cells. The transfer of some of these proteins from cauda

epididymal fluid to sperm surface is temperature sensitive, being more

efficient at 32 – 37ºC at an optimal pH of 6.0–6.5; excess ambient

temperature prevents the transformation of these proteins and sperm

maturation is not completed (Freenette et al., 2002). In spermatozoa,

clusterin protein is suggested to be a survival gene, the transcription of

which is upregulated in physiologically adverse conditions (Ibrahim et al.

2001)). In increased scrotal temperature (heated for 4 days by insulation

bags), Ibrahim et al. (2001) reported increased spermatozoal apoptotic

changes associated with high percentage of clusterin in Montadale and

Texel cross rams. The significantly higher abnormal sperm percent

reported for the unshaded rams during the experimental period compared

with the values obtained for the shaded rams indicates the extent of

harmful effects of direct exposure to solar radiation on spermatogenesis

under tropical conditions.

The normal secretions of testes, epididymis and accessory genital

glands contribute in maintaining normal semen pH, in addition to sperm

cell concentration (Hafez, 1980). In the current results, the significantly

lower semen pH reported for the shaded rams in the second week of the

experimental period (Table 4.20) could be attributed to a decrease in the

secretion of the accessory genital glands.

4.4.2. Exposure to solar adiation and exhaustion test


The results obtained in the present study indicate that the

exhaustion test implemented by frequent electro-ejaculation of Desert

rams was associated with haematological changes.

In both shaded and unshaded rams, the PCV level declined

following the exhaustion test (Table 4.22). In the shaded rams, the PCV

values obtained post-exhaustion in the three consecutive days were

significantly lower compared to pre-exhaustion state. This could be

attributed to alterations in vasopressin secretion and water balance in

response to cortisol secretion. Parker et al. (2003) indicated that in

stressed sheep, plasma cortisol increases and enhances the secretion of

vasopressin and a consequent reduction in water loss occurs, resulting in

low PCV.

The decrease in PCV could be attributed to a transient expansion of

plasma volume to defend against water loss during frequent ejaculation

and heat stress through sweating and panting. Erickson (1993) reported

that an increase of plasma volume in equines and athletes in response to

endurance exercise may serve to defend against excessive water loss

during protracted work and heat stress by induced hypervolaemia as a

negative water balance from increased water loss. However, the

significant reduction in PCV level observed in the post-exhaustion state

during the third day only in the unshaded rams (Table 4.23) is clearly

related to heamodilution which resulted from heat stress, increased water

consumption and accentuation by excess muscle contraction associated

with frequent ejaculation.

The present results indicate that the exhaustion test was associated

with significantly lower total leukocyte count (TLC). In the shaded group

of rams, the significantly lower TLC observed post-exhaustion in the first

and second day compared with the pre-exhaustion value (Table 4.24)

could be attributed to the effects of increase in the secretion of

adrenocortical steroids. Swenson (1993) indicated that adrenocorticoids

may cause an increase in antibodies concentration in the blood through

dissolution of lymphocytes into lymphoid tissue resulting in

lymphopenia. The reduction in TLC could also be related to increase in

blood and lymph flow to the contracting muscles. Ganong (2003)

indicated that during exercise, the increase in blood flow to the active

muscles was associated with vasodilatation. In unshaded rams, the

significant reduction in TLC in the first and third day of the experimental

period (Table 4.25) could be related to the combined effects of prolonged

heat stress and frequent ejaculation.

Generally, the exhaustion test did not induce significant changes in

differential leukocyte count. However, the exhaustion test significantly

increased the ratio of monocytes in the shaded group of rams in the

second and third day of the experimental period (Table 4.26). This could

be attributed to a reduction in ACTH level and cortisol secretion as the

reduction in monocytes ratio in the first day of exhaustion may indicate

the predominance of ACTH. Erickson (1993) indicated that high cortisol

level reduces the ratio of monocytes.

The current results revealed that in the shaded rams, the exhaustion

test significantly decreased the serum total protein level in the third day

of the experimental period (Table 4.28). However, the exhaustion test

significantly reduced the total protein level post-exhaustion in the second

and third day compared with the pre-exhaustion values (Table 4.28). This

could be attributed to increased lymph flow during frequent ejaculation.

Ganong (2003) indicated that during exercise, the lymph flow is greatly

increased, limiting the accumulation of interstitial fluid in an effect

greatly increasing its turnover. In the unshaded rams, the significant

reduction in total protein level in the first and second day of exhaustion

test compared with pre-exhaustion state (Table 4.29) could be associated

with an increase in water intake and haemodilution, in addition to stress

induced by frequent ejaculation.

In the present study, the exhaustion test significantly increased

serum urea concentration in the third day of the experimental period in

the shaded rams (Table 4.32). This could be related to increase in the rate

of protein catabolism. Erickson (1993) indicated that in exercise in

endurance horses the consistent increase in plasma urea level is primarily

attributed to increase in the rate of protein catabolism.

In the current results, the exhaustion test generally increased

plasma glucose concentration in both groups of rams. In the shaded rams

(Table 4.34) the exhaustion test significantly increased glucose level in

the third day of the experimental period. The exhaustion test also

significantly increased the glucose level in the first and third day

compared to the pre-exhaustion values. As exhaustion test constitutes a

stressful condition, an increase in the level of glucocorticoids will

influence the plasma concentrations of energy substrates including

glucose. The actions of glucocorticoids include increased hepatic

glucogenesis and gluconeogene-sis. Glucose 6-phosphate activity is

increased and the plasma glucose level increases. Glucocorticoids exert

an anti-insulin action in the peripheral tissues (Erickson, 1993; Bland et

al., 2000), which increases the blood glucose level. For the unshaded

rams, the exhaustion test significantly increased plasma glucose level in

the post-exhaustion state for the three days (Table 4.35). This response

could be attributed to the combined effects of heat stress and exhaustion

test, as heat stress increases gluconeogenesis (Kamal et al., 1970).

Furthermore, a high level of epinephrine maintained during exhaustion

test stimulates the conversion of muscle glycogen to glucose phosphate.

During exercise, enzymes produced (e.g. tissue lipase) stimulate glucose

synthesis, hepatic glycogenolysis and lipolysis; these actions facilitate

metabolism to provide additional fuel (Erickson, 1993).


In the present study, frequent ejaculation and exposure to solar

radiation influenced semen characteristics. The results indicate that the

exhaustion test significantly reduced the ejaculate volume in the last

collection during the three days in shaded rams (Table 4.36). This is

clearly associated with the continuous withdrawal of semen from the

epididymal reserve and slow replacement by testicular, epididymal and

accessory genital glands secretions. Similar findings were reported in

frequently ejaculated Desert rams (Galil and Galil, 1982a) and Konya

Merino rams (Kaya et al., 2002). Frequent ejaculation of unshaded rams

significantly reduced the ejaculate volume of the last collection of the

first day (Table 4.37). This could be attributed to the effects of thermal

stress and frequent ejaculation on the testes and accessory genial glands

function.

The exhaustion test of shaded rams significantly reduced the sperm

individual motility (IM) of first collection of the last two days and last

collection of the third day (Table 4.40). This could be associated with the

time needed for spermatozoa in the epididymal transit to acquire their

ability of motility. Under normal conditions, the spermatozoa stay for

about 16 days in the epididymis of rams (Garner and Hafez, 2000).

Howarth (1969) reported that more than 3 days are required for the

passage of spermatozoa in epididymal duct for frequently ejaculated

rams. The reduction in sperm IM may also be related to insufficient

supply of Ca2+ and Mg ions from epididymal duct fluid. Kaya et al.

(2002) reported that in frequently ejaculated Konya rams, these cations

were positively correlated with sperm IM. Similarly, successive

collection of semen samples was associated with decrease in sperm IM in

Sudanese Desert rams (Galil and Galil, 1982a).

In the unshaded rams, the exhaustion test significantly lowered

sperm IM in day I for the first collection and day 3 for the last collection

(Table 4.41). This could be attributed to exhaustion of the epididymal

sperms store. Also the reduction in sperm IM could be attributed to the

low availability of energy sources in seminal plasma which include

fructose and adenosine triphosphate (ATP). The reduction in energy

sources is related to the reduction in testicular, epididymal and

accessory genital glands secretions due to thermal effects during exposure

to solar radiation. This finding indicates that exposure of Desert rams to

direct solar radiation under tropical conditions reduces sperm IM.

Consequently the fertility and ability of successful fertilization of ewes is

reduced.

The significant reduction in sperm cell concentration observed in

the first and last collections in the last two days and in the last collections

of the first and second day compared to first collection in shaded rams

(Table 4.42) in response to frequent ejaculation is clearly related to

depletion of epididymal sperm content. The tail of the epididymis

contains about 70% of the total number of spermatozoa compared to

excurrent ducts. In rams, the seminiferous tubules cycle takes 10 days

with different stages of spermatogenic wave; successive collection of

semen with lower rate of replacement of spermatozoa may result in

epididymal reserve depletion. Similar findings of reduced sperm cell

concentration in response to successive collection of semen were reported

in Desert rams (Galil and Galil, 1982a) and Merino rams (Salamon, 1962,

1964b). In Najdi rams, frequent ejaculation decreased sperm cell

concentration (Galil et al., 1984). Frequent ejaculation was also

associated with decrease in sperm cell concentration in Konya Merino

rams (Kaya et al., 2002). On the other hand, subjection of male goats to

successive collection of semen decreased sperm cell concentration (Ritar

et al., 1992; Oyeyemi et al., 2001).

In unshaded rams the exhaustion test significantly decreased the

sperm cell concentration in the first collection of the last two days and

significantly increased it in the last collection in the third day (Table

4.43). The reduction in sperm cell concentration could be associated with

interruption in spermatogenic cycle and consequently a reduction in the

number of spermatozoa produced. However, the increase in sperm cell

concentration during exposure to heat stress could be attributed to the

reduction in the ejaculate volume reported in this study. The findings

indicate that sperm cell concentration values reported were lower in

exhausted unshaded rams compared to values obtained for exhausted

shaded rams.

The present results indicate that the combined effects of exposure

to solar radiation and exhaustion test of Desert rams significantly reduced

the incidence of living sperms in the first collection of the third day and

increased it in the last collection of the third day (Table 4.45). The

reduction in living spermatozoa in the former state could be related to the

biochemical changes in spermatozoa, in addition to the influence of high

ambient temperature which alters the scrotal thermoregulation

mechanism. Kaya et al. (200) reported that frequent ejaculation of Konya

Merino rams increased sperm membrane damage and release of Aspartate

Amino Transaminase (ATA), Glutamic Pyruvic Transaminase (GPT) and

Lactate Dehydrogenase (LDH) in seminal plasma. In frequently

ejaculated Desert rams, Galil and Galil (1982a) reported low live sperm

percent.

The results indicate that the exhaustion test significantly reduced

the incidence of abnormal sperm in the first collection of the last two

days (Table 4.46). This reduction is clearly related to inadequate

epididymal maturation and continuous withdrawal of abnormal sperms

obtained. However, the increase in abnormal sperm incidence reported in

the last collection of the second day compared to the first collection value

could be associated with low calcium ions and an inadequate epididymal

maturation. Kaya et al. (2002) reported that calcium ion (Ca2+) is

negatively correlated to abnormal sperms percent in frequently ejaculated

Konya Merino rams. In frequently ejaculated Desert rams, the increase in

abnormal sperm percent was attributed to inadequate epididymal

maturation (Galil and Galil, 1982a). However, in the current results,

frequent ejaculation of unshaded rams, significantly reduced the

incidence of abnormal sperms in the first collection of the last two days

and in the last collection of the third day (Table 4.47). This response

could be attributed to reduction in the abnormal sperm percent produced

during exposure to solar radiation ,which is related to failure of the

scrotal thermoregulation mechanism. Kastelic et al. (1996) reported that

in rams, thermal stress disturbs the cooling of testicular arterial blood

exchange in spermatic cord. However, the significantly high abnormal

sperm percent reported post-exhaustion in the second day of the

experimental period could be related to the effects of frequent ejaculation.

The results showed that frequent ejaculation of shaded rams was

associated with increase in semen pH of the first collection of the last two

days. This could be attributed to the observed increase in the volume of

seminal plasma in the ejaculate. Milovanov (1962) indicated that semen

pH was influenced by the proportion of alkaline seminal plasma to the

acidic epididymal secretion. Also the reported increase in semen pH

could be attributed to changes in pH of spermatozoa related to

biochemical changes associated with frequent ejaculation (Kaya et al.,

2002). Also a low fructose content of frequently ejaculated semen could

be responsible for high semen pH. In Desert rams, Galil and Galil

(1982b) reported an increase in seminal plasma and low fructose

concentration in association with frequent ejaculation.

4.5. Summary

1. Eight entire Desert rams were used to investigate the effects of

exposure to solar radiation on thermoregulation, blood

composition and semen characteristics. The effects of exposure

to solar radiation and exhaustion test (frequent ejaculation) for

3 days on blood constituents and semen characteristics were

also examined.

2. The rectal temperature (Tr) of rams exposed to solar radiation

was significantly higher at 7: 00 a.m. and 2: 00 p.m. compared

to respective values obtained for the shaded rams.

3. The respiration rate (RR) values of unshaded rams were

significantly higher at 7: 00 a.m. and at 2: 00 p.m. compared to

values obtained for shaded rams.

4. Exposure to solar radiation significantly lowered the ratio of

eosinophils in the third week of the experimental period

compared to values reported for the shaded rams. The ratio of

monocytes increased significantly in the last two weeks of

exposure to solar radiation. Exhaustion test significantly

lowered TLC of shaded rams in the first and second day

compared to the initial values. In unshaded rams , exhaustion

test significantly reduced TLC in the first day compared to pre-

exhaustion values. The monocytes ratio was significantly

higher in the last two days of exhaustion test of shaded rams

compared to day I.

5. The PCV level of exhausted shaded rams was significantly

lower during the experimental period. Exposure to solar

radiation and exhaustion test significantly lowered the PCV

level in day 3.

6. The serum total protein level increased significantly in response

to exposure to solar radiation compared to the respective values

reported for the shaded rams. The total protein level was

significantly decreased in response to exhaustion test in days 2

and 3 compared to day 1. In unshaded rams, the exhaustion test

significantly decreased serum total protein level in the first and

second day compared to the pre-exhaustion value.

7. The serum albumin level was lower in unshaded rams

compared to values obtained for control group, and the value

obtained for the second week attained the significance level.

8. The serum urea level was significantly lower in both groups of

rams in the last week of the experimental period. Serum urea

level significantly increased in shaded rams in response to

exhaustion test, particularly in day 3.

9. The plasma glucose level was significantly lower in the last

week of the experimental period in unshaded rams compared to

respective value of the shaded rams. Post-exhaustion, the

plasma glucose level of shaded rams was significantly higher in

days 1 and 3 compared to the pre-exhaustion values .In

unshaded rams, the exhaustion test significantly increased the

glucose level in the three days compared to the pre-exhaustion

values.

10. Exposure to solar radiation significantly lowered the ejaculate

volume, particularly in the third week. The ejaculate volume

was significantly lower in unshaded rams during the second

week of the experimental period compared to the value of

shaded rams. The ejaculate volume of shaded rams was

significantly decreased in response to exhaustion test in the

three days compared to the pre- exhaustion value.

.

11. The sperm mass motility (MM) was consistently reduced

during exposure to solar radiation and the value reported in the

last week was significantly lower compared to the value of

week 1.

12. The sperm individual motility (IM) was significantly lowered

in response to exposure to solar radiation in the last two weeks.

The unshaded rams had significantly lower values of IM in the

last two weeks compared to the shaded rams. Sperm IM was

significantly reduced post-exhaustion in shaded rams in days 1

and 3. The IM values of exhausted unshaded rams obtained in

the last collection were significantly higher in the first day and

significantly lower in third day compared to the respective

values obtained in the first collections.

13. The sperm concentration was significantly lower in the last two

weeks of experimental period in the unshaded rams. In the first

week of the experimental period, the unshaded rams had

significantly higher values of sperm concentration compared to

the shaded rams. In shaded rams, the values of sperm

concentration obtained, post -exhaustion, in the last collection

in the first and second day were significantly lower compared

to the respective values of the first collection. In unshaded

rams, sperm concentration of the last collection of day 1 was

significantly lower compared to the first collection , while it

was significantly higher in day 3 compared to the initial

values.

14. The percentage of live sperms was significantly lower in the

first week of the experimental period in the unshaded rams. The

live sperm percent was also significantly lower in the first week

of exposure to solar radiation compared to the respective value

of shaded group. The percentage of live sperm of exhausted

unshaded rams was significantly higher in the third day of the

experimental period compared to the pre-exhaustion value.

15. The percentage of abnormal sperms was significantly higher in

the last two weeks of exposure to solar radiation. The values of

the unshaded rams were significantly higher compared to

respective valuess reported for the shaded rams during the

experimental period. In shaded exhausted rams, the percentage

of abnormal sperms was significantly higher in the second day

compared to respective pre-exhaustion values. In the unshaded

exhausted rams, there was a significant reduction in the

percentage of abnormal sperms of the last collections of days 1

and 3, and an increase in the last collection of day 2 compared

to the respective pre-exhaustion values.

CHAPTER FIVE

EFFECTS OF SEASONAL CHANGES IN THERMAL

ENVIRONMENT AND SHEARING ON

THERMOREGULATION, BLOOD CONSTITUENTS

AND SEMEN CHARACTERISTICS

5.1 Introduction

Exposure of sheep to climatic stress and seasonal changes affect their heat

balance and physiological responses. Heat tolerance is a complex association between

ambient temperature, humidity, radiation, avenues of evaporative heat loss and coat

characteristics (Hofman and Riegle, 1977).

In the tropics, the insulation of the hairy coat of sheep increases with coat

thickness and hair density (Bennett and Hutchinson, 1964). In the hot humid tropics,

where high ambient temperature and relative humidity may contribute more to heat

stress than solar radiation, a thick coat may not be an advantage; however, wooly

coats can be an advantage in animals that pant to lose heat (Yeates et al., 1975a). The

thermal resistance to the flow of heat from skin to the surface of the pelage depends

upon the entrapped air which occupies over 95% of the volume of hair coat. In sheep,

a protective fleece will help to combat the effects of radiation through the insulation

and cutaneous evaporation (Hofmeyr et al.1969; McArthur and Monteith, 1980). In

rams, the scrotum is ventrally located and it is protected from direct solar radiation. In

hot environments, a heavy scrotal wool growth will impede evaporation, thus

preventing the efficiency of cooling and interfering with spermatogenesis (Kastelic et

al., 1996).

Coat shedding in ruminants is considered as a seasonal phenomenon

controlled mainly by photoperiod and nutrition (Graham et al., 1959, Lincoln and

Richardson, 1998). However, in the tropics as variation in day length is less,

indigenous sheep breeds do not exhibit seasonality in coat characteristics (Mcleroy,

1962 c).

Shearing of heavily wooled animals can be used as an appropriate tool for the

prevention of hyperthermia (Fowler, 1989, 1994). However, the surface temperature

of skin rapidly increases after removal of fleece (Gerken, 1997).Shearing of sheep is

an ameliorative measure when they are kept under intensive husbandry system, and it

is advantageous when the weather is moderate and the animal is under shade (Azamel

et al., 1987; Ahmed and Abdelatif, 1992).

Newly shorn sheep are susceptible to cold and heat stress as shearing results in

changes in the physical characteristics of the fleece. This is usually associated with

doubling of the reflected sunlight, an increase in penetration of radiation to the skin,

and marked increase in total energy absorbed (Macfarlane et al.,1966). Consequently

the demand for evaporative cooling increases and the metabolism of energy and water

is disturbed. Shearing of Mediterranean Comisana breed of sheep, in mid-spring

(16ºC-28ºC) caused a fall in skin temperature, and low body heat production

(Piccione et al., 2002). Winter shearing of sheep increased food intake to meet energy

demands caused by increase in heat loss (Vipond et al., 1987). However, in harsh

desert conditions, shearing of sheep during the cold season might be physiologically

advantageous compared to summer shearing , as it facilitates heat loss and increases

food consumption (Elhadi, 1988).

Exposure of shorn sheep to cold reduces their productivity through

modification of digestion and metabolic and endocrine functions (Sano et al.,2002).A

low apparent digestibility of dry matter and organic matter was reported in shorn

Suffolk wethers exposed to cold environment (Kennedy and Milligan, 1973; Westra

and Christopherson , 1976; Kennedy et al., 1976,1982) . Previous studies on sheep

have investigated the influences of shearing on their skin temperature, respiration rate

and water turnover (Elhadi, 1988) and heat tolerance(Cloete et al,2000). Also the

effects of shearing and walking exercise on thermoregulation, food utilization and

blood metabolites in Desert rams were carried out (Ahmed and Abdelatif, 1992).

However, there is dearth of information regarding the effects of interaction between

shearing and thermal environment on blood metabolites and seminal traits of Desert

rams. The main objective of this experiment was to investigate the effects of shearing

Desert rams during winter and summer on thermoregulation, blood constituents and

semen characteristics. The effects of season, shearing and fasting on blood

constituents were also investigated in both seasons.


The experimental plan is shown in Table 5-1. Eight Desert rams were used in

the experiment. The rams were randomly assigned to two groups of 4 rams each. The

control group was kept unshorn with intact pelage, the mean length of hair was about

1.5cm, and the treated group was shorn. Shearing was performed using a manual

shearing machine , the mean length of hair left was approximately 0.5 cm in both

seasons .Both groups of rams were allowed an adaptation period of 2 weeks. This

period was followed by 4 weeks of experimental measurements. The measurements

were conducted with a similar protocol during winter and summer at the University

Farm at Shambat. The animals were allowed to graze daily from 7:00 a.m to 2:00

p.m., and they were allowed free access to tap water. The measurements of rectal

temperature (Tr) and respiration

Table 5.1 Experimental plan

Experimental period Treatment Weekly

measurements

Weekly

Sampling Analysis

Winter

(20 Jan-22 Feb. /2001)

Summer

(3 May- 5 June/2001)

-Unshorn

-Shorn

-Tr (7:00 a.m.,

2:00 p.m.).

-RR(7:00 a.m.,

2:00p.m.).

-Scrotal

circumference.

-Blood

-Semen

-Blood parameters.

-Seminal traits.

On the last day of the

fourth week before

fasting.

Sampling -Blood samples

Analysis

-Blood parameters.

Three days fasting

period.

-None

-None

On the first day

following the fasting

period.

-Blood samples

-Blood parameters.

rate (RR) were performed weekly in the morning (7:00 a.m.) and in the afternoon

(2:00 p.m.) under broken shade for 4 weeks. Blood and semen samples were also

collected weekly in the morning (8:00 a.m.) for 3 weeks. In the last day of the 4th

week, blood samples were collected. Thereafter, rams were fasted for three successive

days, there were no experimental measurements during this period. Blood samples

were collected after the third day of fasting.

Blood samples were used for determination of PCV and total and differential

leukocyte counts. Serum samples were used for the measurements of the

concentrations of total protein, albumin and urea and plasma samples were used for

the determination of glucose concentration. Semen samples were used for the

determination of ejaculate volume, and the analysis of mass and individual motility,

sperm cell concentration, live sperms percent, morphologically abnormal sperms and

semen pH. Measurements of scrotal circumference were performed weekly.

The climatic data were obtained from Shambat Meteorological Station which is

located about 1Km from the site of the experiment at the University Farm. Table 5.2

shows the ambient temperature (Ta) and relative humidity (RH) during the

experimental period.

Table 5.2 The ambient temperature (Ta) and relative humidity (RH)

during the experimental period.

Season

Winter Summer

Ta (ºC) Ta (ºC)

Time

(Weeks)

Max. Min. Mean.

RH(%)

Mean Max. Min. Mean.

RH(%)

Mean

1 28.3 12.7 20.0 23.0 42.2 23.8 33.0 14.0

2 32.4 14.1 23.5 27.0 43.3 22.9 33.1 14.0

3 30.4 14.6 22.5 25.0 41.5 27.0 34.3 17.0

4 31.8 14.5 22.2 27.0 41.3 26.3 38.8 24.0

5 31.2 16.3 24.3 20.0 41.6 23.9 32.8 19.0

Winter (20 January – 22 February, 2001).

Summer (3 May – 5 June, 2001).

5.3. Results

The effects of seasonal changes in thermal environment and

shearing on thermoregulation, blood constituents and semen

characteristics, and the combined effects of these factors and fasting on

blood composition were studied in Desert rams.

5.3.1 Effect of season on the responses to shearing

5.3.1.1 Thermoregulation

5.3.1.1.1 Rectal temperature (Tr)

Table 5.3 shows the results of the effects of season and shearing on

rectal temperature (Tr) of rams measured in the morning at 7:00 a.m. In

both seasons, shorn rams had significantly (p<0.05) lower values of Tr

compared to values obtained for unshorn rams. Both unshorn and shorn

rams had higher Tr values in summer; the seasonal change in Tr were

more pronounced in shorn rams.


rectal temperature (Tr) in the afternoon at 2:00 p.m. Shearing reduced Tr

in both seasons. However, the shearing induced decline in Tr was

significant (p<0.05) in summer. For both shorn and unshorn rams, Tr

values were higher in summer compared to winter values. The seasonal

change in Tr was significant (p<0.05) in unshorn rams. Both groups of

rams showed a diurnal pattern in Tr irrespective of season. The diurnal

changes in Tr for unshorn rams were 1.0 and 0.82ºC in summer and

winter, respectively. The corresponding changes in Tr for shorn rams

were 1.08 and 2.03ºC, respectively.

Table 5.3. Effects of season and shearing on rectal temperature, Tr (ºC) of

Desert rams at 7: 00 a.m .

( n= 16, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A38.23 a

± 0.07

A38.98 a

± 2.23 NS

Shorn B37.07 a

± 0.19

B37.84 a

± 0.12 NS

SL * *

Mean values within the same row bearing similar superscripts (small) are


Mean values within the same column bearing different superscripts

(capital) are significantly different.


* Significant at p<0.05


Table 5.4. Effects of season and shearing on rectal temperature, Tr (ºC) of Desert rams at 2: 00 p.m..

(n =16,Mean ± S.E.M.).

Treatment Season SL

Winter Summer

Unshorn A39.05 b

± 0.06

A39.98 a

± 0.06 *

Shorn A38.90 a

± 0.05

B38.92

± 0.08a NS

SL NS *

Mean values within the same row bearing different superscripts are


Mean values within the same column bearing different superscripts are



*: Significant at p<0.05


5.3.1.1.2 Respiration rate (RR)


the respiration rate (RR) of rams in the morning at 7:00 a.m. In both

seasons, RR was slightly lower in shorn rams compared to the control.

Both unshorn and shorn rams had significantly (p< 0.05) higher RR

values during summer compared to winter values.


the respiration rate (RR) in the afternoon at 2:00 p.m. Shearing was

associated with a significant (p<0.05) decrease in RR in both seasons.

The unshorn and shorn rams had significantly (p< 0.001) higher RR

values in summer compared to respective values obtained in winter. Both

groups of rams showed a diurnal pattern in RR during summer and

winter. For the unshorn rams, the diurnal changes in RR were 48 and 16

breaths/min, for summer and winter, respectively. The corresponding

changes in shorn rams were 31 and 6 breaths/min, respectively.


5.3.1. 2.1 Packed cell volume (PCV)


the PCV level. In both seasons, there was no significant effect of shearing

on PCV level. Both unshorn and shorn rams had lower PCV values in

summer. However, the decrease in PCV was significant (p< 0.05) in

shorn rams.

5.3.1.2.2 Leukocytic indices

Table 5.8 shows the results of the effects of season and shearing on the total leukocyte count (TLC). In both seasons, shearing did not influence the TLC significantly. The unshorn and shorn rams maintained higher TLC values in winter compared to the respective values

obtained in summer.

Table 5.5. Effects of season and shearing on respiration rate, RR (breaths/min)


(n = 16, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A23.75 b

± 0.77

A31.75 a

± 3.90 *

Shorn A21.50 b

± 0.72

A30.25 a

± 4.52 *

SL NS NS



Mean values within the same column bearing similar superscripts (capital) are not





Table 5.6. Effects of season and shearing on respiration rate, RR (breaths/min)

of Desert rams at 2: 00 p.m.

(n=16, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A39.44 b

± 4.11

A79.50 a

± 7.80 ***

Shorn B27.75 b

± 1.29

B65.75 a

± 6.94 ***

SL * *






*: Significant at p< 0.05

***: Significant at p<0.001.


Table 5.7. Effects of season and shearing on PCV (%) in Desert rams.

(n = 16 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A28.63 a

± 1.32

A26.00 a

± 0.79 NS

Shorn A29.06 a

± 1.11

A25.81 b

± 0.73 *

SL NS NS








Table 5.8. Effects of season and shearing on total leukocyte count, TLC (×103/µl)

of Desert rams.

(n = 16, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A6.33 a

± 0.54

A6.28 a

± 0.44 NS

Shorn A6.11 b

± 0.401

A5.25 b

± 0.303 NS

SL NS NS

Mean values within the same row or column bearing similar superscripts are not





the differential leukocyte count (DLC). The seasonal changes in the ratio

of lymphocytes were not significant. However, in both seasons, the ratio

of lymphocytes was lower in shorn rams. There was no significant change

in the ratio of neutrophils related to season. The ratio of neutrophils was

higher in shorn rams in both seasons. The ratio of eosinophils was higher

in winter in both unshorn and shorn rams. However, the ratio of

eosinophils was higher in shorn rams in both seasons compared to the

values obtained for the control group. The seasonal changes in the ratio of

monocytes were not significant. The ratio of monocytes was lower in

shorn rams in summer, and it was lower in unshorn rams in winter.


Table 5.10 shows the results of the effects of season and shearing

on serum total protein concentration. Shearing resulted in a slight

increase in total protein level in winter and a slight decrease in summer.

For the unshorn and shorn rams, the total protein level was slightly higher

in winter compared to respective summer values.

5.3.1.2.4 Serum albumin


on serum albumin concentration. Shearing was associated with a slight

decrease in the albumin level in winter and an increase in summer. The

albumin level was higher during winter compared to summer value in

both groups of rams.The increase obtained for the unshorn rams was

significantly (p <0.05) higher.


Table 5.12 shows the results of the effects of season and shearing on serum urea concentration. In both seasons, the serum urea concentration was slightly higher in shorn rams.

For both unshorn and shorn rams, the

Table 5.9. Effects of season and shearing on differential leukocyte count, DLC

in Desert rams.

(n = 16, Mean ± S.E.M.).

Season

Winter Summer Cell type

(%)

Unshorn Shorn Unshorn Shorn

SL

Lymphocytes 59.00 a

± 2.51

54.06 a

± 2.01

58.81 a

± 1.51

56.50 a

± 1.65 NS

Neutrophils 34.13 a

± 2.85

38.31 a

± 2.20

34.31 a

± 1.50

38.06 a

± 1.73 NS

Eosinophils 2.25 a

± 0.72

2.50 a

± 0.52

1.13 a

± 0.24

1.63 a

± 0.36 NS

Monocytes 4.63 a

± 0.63

5.13 a

± 0.88

5.75 a

± 0.99

3.81 a

± 0.59 NS

Mean values within the same row bearing similar superscripts are not significantly

different.


NS: Not significant

Table 5.10. Effects of season and shearing on serum total protein concentration (g/dl)

in Desert rams .

(n = 16 , Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A7.34 a

± 0.21

A7.29 a

± 0.15 NS

Shorn A7.40 a

± 0.17

A7.13 a

± 0.19 NS

SL NS NS





Table 5.11. Effects of season and shearing on serum albumin concentration (g/dl)

in Desert rams .

(n= 16 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A4.13 a

± 0.11

A3.50 b

± 0.05 *

Shorn A3.90 a

± 0.08

A3.55a

± 0.05 NS

SL NS NS








Table 5.12. Effects of season and shearing on serum urea concentration (g/dl)

in Desert rams.

(n = 16 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A22.48 a

± 2.42

A19.70 a

± 1.15 NS

Shorn A24.13 a

± 2.28

A20.32 a

± 1.34 NS

SL NS NS




NS: Not significant

serum urea level was slightly higher in winter compared to the respective

values obtained in summer.



on plasma glucose concentration. The glucose level was higher in shorn

rams in both seasons. However, the increase that occurred in glucose

level was significant (p< 0.05) only in winter .The season did not

influence the plasma glucose level in unshorn rams. However, the shorn

rams had significantly (p< 0.05) higher plasma glucose level in winter

compared to the summer value.




on the ejaculate volume. Shearing did not affect significantly the

ejaculate volume irrespective of season. The ejaculate volume was

significantly lower during summer in the unshorn (p< 0.05) and shorn

(p<0.01) rams.



on sperm MM. Shearing slightly lowered sperms MM in both seasons .

The season influenced the sperm MM in both groups of rams; the values

obtained during summer were significantly (p<0.05) lower compared to

the respective winter values.



on sperm IM.Shearing significantly reduced the sperm IM during winter

(p<0.01) and summer (p<0.05). In both groups of rams, summer induced

a decline in sperm IM; The unshorn rams had significantly (p<0.05)

lower IM in summer compared to winter value.

Table 5.13. Effects of season and shearing on plasma glucose concentration (g/dl)

in Desert rams .

( n = 16, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn B56.01 a

± 1.38

A55.68 a

± 1.44 NS

Shorn A64.40 a

± 2.89

A58.10 b

± 1.51 *

SL * NS








Table 4.14 Effects of season and shearing on ejaculate volume (ml) in Desert rams.

(n =12, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A1.32 a

± 0.13

A0.68 b

± 0.12 *

Shorn A1.39 a

± 0.09a

A0.55 b

± 0.16 **

SL NS NS



Mean values within the same column bearing similar superscripts(capital) are not



*: Significant at p< 0.05



Table 5.15. Effects of season and shearing on sperm mass motility ,MM (0–5)

in Desert rams .

( n = 12 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A3.56 a

± 0.40

A3.38 b

± 0.14 *

Shorn A3.53 a

± 0.18a

A3.25 b

± 0.36 *

SL NS NS








Table 5.16. Effects of season and shearing on sperm individual motility, IM

(%) in Desert rams.

(n =12 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A53.33 a

± 6.40

A41.56b

± 4.02 *

Shorn B38.00 a

± 3.23

B34.18 a

± 34.17 NS

SL ** *







**: Significant at p<0.01

NS: Not significant



on sperm cell concentration .Shearing was associated with relative

increase in sperm cell concentration in winter and summer. During

summer, the sperm cell concentration was slightly lower in both groups

of rams compared to winter values.



on the incidence of live sperm. Shearing of rams had no significant effect

on live sperm percent in both seasons. The live sperms percent was

significantly (p< 0.05) lower during summer in the unshorn and shorn

rams compared to the respective values obtained during winter.



on the incidence of abnormal sperm. Shearing slightly increased the

abnormal sperm percent in both seasons. The abnormal sperms percent

was significantly (p<0.01) higher during summer compared to the

respective value obtained during winter in the unshorn and shorn rams.

5.3.1.3.7 Semen pH


on semen pH. In both seasons, shearing was associated with a slight

increase in semen pH. In both groups of rams, the semen pH values

were slightly higher in summer compared to winter.

5.3.1.4 Scrotal circumference (SC)


on the SC. In both seasons, shearing had no significant effect on SC. The

season did not influence SC significantly.

Table 5.17.Effects of season and shearing on sperm cell concentration (x109/ml) in Desert rams . (n = 12, Mean ± S.E.M.).

Season Treatment

Winter Summer

SL

Unshorn

A1.59 a

±0. 20

A1.53 a

±0. 52 NS

Shorn

A2.08 a

± 0.18

A1.64 a

±0. 65 NS

SL NS NS




NS: Not significant

Table 5.18 Effects of season and shearing on the incidence of live sperm

(%) in Desert rams.

(n = 12, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A98.59 a

± 0.33

A96.19 b

± 0.83 *

Shorn A98.14 a

± 0.53

A95.90 b

± 0.67 *

SL NS NS








Table 5.19. Effects of season and shearing on the incidence of abnormal sperm

(%) in Desert rams.

(n = 12 ,Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A1.39 b

± 0.26

A5.08 a

± 1.21

**

Shorn A2.03 b

± 0.47

A6.58 a

± 1.81

**

SL NS NS








Table 5.20. Effects of season and shearing on semen pH in Desert ram.

(n =12, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A7.56 a

± 0.04

A7.61 a

± 0.11 NS

Shorn A7.67 a

± 0.06

A7.72 a

± 0.10 NS

SL NS NS





Table 5.21. Effects of season and shearing on scrotal circumference (cm) of Desert

rams.

(n = 12, Mean ± S.E.M.).

Season Treatment

Winter Summer SL

Unshorn A30.91 a

± 0.26

A31.91 a

± 0.37 NS

Shorn A29.53 a

± 1.67

A30.59 a

± 0.42 NS

SL NS NS





5.3.2 Effects of season, shearing and fasting on blood composition

5.3.2.1 Packed cell volume (PCV)

Table 5.22 shows the results of the effects of season, shearing and

fasting on PCV level. In both seasons, shearing did not affect the PCV

level significantly before and after fasting. For both groups of rams, the

post- fasting value of PCV was slightly lower in winter compared to the

pre-fasting levels. However, during summer the post- fasting value was

slightly higher in control rams and slightly lower in shorn rams compared

to the pre-fasting values.

5.3.2.2 Leukocytic indices


fasting on total leukocytes count (TLC). In both groups of rams, fasting

had no significant effect on TLC during summer and winter. However,

the results indicate that for unshorn rams in both seasons, fasting slightly

decreased TLC. For shorn rams, in both seasons, fasting was associated

with increase in TLC.


fasting on differential leukocyte count (DLC).During winter ,fasting

significantly (p<0.05) lowered the ratio of lymphocyte of shorn rams

compared to the unshorn.The post-fasting value of lymphocytes ratio was

significantly (p<0.05) lower in shorn rams during summer compared to

the values obtained for winter. The season and fasting did not influence

the lymphocytes ratio of unshorn rams.

Fasting was associated with an increase in the ratio of neutrophils in the shorn rams during winter and summer

compared to the unshorn, and

Table 5.22. Effects of season, shearing and fasting on PCV (%) in Desert rams .

(n = 8 ,Mean ± S.E.M.).

Season

Winter Summer Treatment

Before

fasting

After

fasting

Before

fasting

After

fasting

SL

Unshorn A29.00 a

± 2.58

A28.50 ab

± 1.06

A23.75 b

± 1.49

A24.75 ab

± 1.03 *

Shorn A29.00 a

± 2.04

A28.50 ab

± 1.66

A26.25 ab

± 0.75

A24.00 b

± 0.41 *

SL NS NS NS NS








Table 5.23. Effects of season, shearing and fasting on total leukocyte count,

TLC (X103/µl) in Desert rams .

(n = 8,Mean ± S.E.M.).

Season


Before

fasting

After

fasting

Before

fasting

After

fasting

SL

Unshorn A6.13 a

± 0.38

A4.87 a

± 0.78

A6.64 a

± 1.19

A5.83 a

± 0.70 NS

Shorn A4.58 a

± 0.52

A6.81 a

± 0.81

A5.01 a

± 0.11

A6.28 a

± 1.52 NS

SL NS NS NS NS





Table 5.24. Effects of season, shearing and fasting on differential leukocyte count,

DLC in Desert rams.

(n := 8,Mean ± S.E.M.).

Season Winter Summer Cell type

(%) Treatment

Before fasting

After fasting

Before fasting

After fasting

SL

Unshorn A56.75 a ± 4.77

A57.00 a ± 4.51

A56.75 a ± 3.45

A54.25 a ± 3.07

NS

Shorn A51.25 b ± 3.42

B48.25 ab ± 3.64

A59.50 a ± 3.18

B46.50 b ± 5.78

*

Lymphocytes

SL NS * NS * Unshorn B33.75 b

± 3.77

A40.25 a ± 5.68

A34.25 b ± 3.90

B40.75 a ± 7.36

*

Shorn A42.50 a ± 3.50

A43.00 a ± 4.53

A32.50 b ± 3.40

A47.75 a ± 4.95

**

Neutrophils

SL * NS NS * Unshorn A3.25 a

± 0.75

A3.50 a ± 1.04

A0.75 b ± 0.48

A1.50 a ± 0.50

*

Shorn A3.25 b ± 0.83

A3.75 b ± 1.25

A1.50 b ± 0.64

A2.75 a ± 0.48

*

Eosinophils

SL NS NS NS NS Unshorn A6.00 a

± 1.29

A4.25 b ± 1.71

A5.75 a ± 1.11

A3.50 b ± 1.26

*

Shorn B3.00 b ± 0.71

A5.00 ab ± 1.58

A6.50 a ± 0.96

A3.00 b ± 0.90

*

Monocytes

SL * NS NS NS

For each parameter, mean values within the same row bearing different superscripts (small) are significantly different.

For each parameter, mean values within the same column bearing different superscripts (capital) are significantly different. SL: Significance level. *: Significant at p< 0.05 *: Significant at p< 0.01 NS: Not significant. the value obtained during summer was significant (p< 0.05) . The post-fasting values of neutrophils ratio was significantly higher during winter and summer (p< 0.05) in

unshorn rams, and during winter (p< 0.01) in shorn rams.

In both seasons, the post- fasting value of eosinophils ratio was slightly higher in shorn rams compared to the values obtained for the unshorn. In both seasons, fasting increased the ratio of eosinophils of the unshorn and shorn rams and the value obtained for summer was significant (p<

0.05). Fasting of shorn rams slightly increased the ratio of monocytes during winter and decreased it during summer compared to the respective values reported for the unshorn group of rams. The post-fasting ratio of monocytes was significantly (p<0.05) lower during summer and winter in the unshorn rams. However, in the shorn rams, the post-fasting ratio of monocytes was slightly higher during winter

and it was significantly (p<0.05) lower during summer. 5.3.2.3 Serum total protein


fasting on serum total protein level. During winter, fasting significantly

(p< 0.05) increased the serum total protein level in shorn rams compared

to the respective values of unshorn rams. Compared to the respective

summer values, the post-fasting values of total protein obtained in winter

were significantly (p< 0.05) lower in the unshorn rams. However, fasting

increased the total protein level of shorn rams in both seasons and the

value obtained during winter was significantly (p< 0.05) higher compared

to summer value.

Table 5.25. Effects of season, shearing and fasting on serum total protein

concentration (g/dl) in Desert rams.

( n = 8,Mean ± S.E.M.).

Treatment Season SL

Winter Summer

Before

fasting

After

fasting

Before

fasting

After

fasting

Unshorn A8.12 a

± 0.34

B6.95 b

± 0.39

A7.48 b

± 0.40

A7.53 b

± 0.70 *

Shorn A7.93 b

± 0.05

A8.38 a

± 0.56

A7.13 b

± 0.31

A7.43b

± 0.30 *

SL NS * NS NS








5.3.2.4 Serum albumin


fasting on serum albumin concentration. In both seasons, fasting of shorn

rams did not significantly influence serum albumin level . Post-fasting,

the serum albumin level was significantly (p< 0.01) increased in unshorn

rams during summer compared to winter values. However, fasting of

shorn rams slightly lowered serum albumin concentration during winter,

and slightly increased it during summer.

5.3.2.5 Serum urea


fasting on serum urea level. During winter, the post- fasting value of urea

was significantly (p< 0.05) higher in shorn rams. In both seasons, the

post-fasting values of serum urea level were significantly (p< 0.01) lower

in unshorn rams. However, in shorn rams, fasting was associated with a

slight increase in serum urea during winter and a significant (p<0.05)

decrease in summer.

5.3.2.6 Plasma glucose


fasting on plasma glucose concentration. In both seasons, the post- fasting

glucose level was significantly (p< 0.05) higher in shorn rams compared

to unshorn. Fasting significantly lowered the plasma glucose

concentration of unshorn rams during summer (p<0.05) and shorn rams

during winter (p<0.05).

Table 5.26 Effects of season, shearing and fasting on serum albumin concentration

(g/dl) in Desert rams.

( n = 8,Mean ± S.E.M.).

Season


Before

fasting

After

fasting

Before

fasting

After

fasting

SL

Unshorn A3.53 b

± 0.19

A3.48 b

± 0.11

A4.08 b

± 0.15

A4.45 a

± 0.09 **

Shorn A3.88 b

± 0.25

A3.70 b

± 0.01

A4.43 a

± 0.11

A4.45 a

± 0.06 *

SL NS NS NS NS



Mean values within the same column bearing similar superscripts(capital) are not




**: Significant at p < 0.01.


Table 5.27 Effects of season, shearing and fasting on serum urea concentration

(mg/dl) of Desert rams.

( n =8, Mean, S.E.M.).

Season


Before

fasting

After

fasting

Before

fasting

After

fasting

SL

Unshorn A23.60 a

± 0.74

B12.28 b

± 2.56

A27.78 a

± 1.54

A18.90 b

± 2.61 **

Shorn A21.75 ab

± 3.70

A23.23 ab

± 3.50

A27.35 a

± 1.32

A14.65 b

± 0.55 *

SL NS * NS NS







**:Significant at p<0.01

NS: Not significant

Table 5.28. Effects of season, shearing and fasting on plasma glucose concentration

(mg/dl) in Desert rams

(n = 8 , Mean ± S.E.M.).

Season


Before

fasting

After

fasting

Before

fasting

After

fasting

SL

Unshorn B49.38 b

± 8.63

B44.50 b

± 3.23

A55.64 a

± 2.53

B42.10 b

± 2.85 *

Shorn A59.63 a

± 3.53

A52.43 b

± 2.86

A56.94 ab

± 3.98

A54.22 b

± 7.03 *

SL * * NS *







NS: Not significant

5.4. DISCUSSION

In this experiment, Desert rams were used to investigate the effects

of shearing during summer and winter on thermoregulation, blood

composition and semen characteristics. The combined effects of shearing

and fasting on blood metabolites were also evaluated.

4.5.1. Seasonal change and shearing

5.4.1.1. Thermoregulation

The results indicate that the thermoregulatory responses of Desert

rams were influenced by season and shearing. The rectal temperature (Tr)

was significantly lower in response to shearing at 7: 00 a.m. in both

seasons (Table 5.3) and at 2: 00 p.m. during summer compared to values

reported for the unshorn rams (Table 5.4). This response is associated

with facilitated heat dissipation via sensible means with the reduction of

hairy coat insulation. Also the response indicates changes in heat balance

of Desert rams induced by seasonal changes in thermal environment.

Mittal and Gohsh (1979) noted that the Tr of shorn Corriedale rams was

positively correlated to the prevailing ambient temperature. Moreover,

Azamel et al. (1987) indicated that shearing of Barki and Barki Merino

cross sheep decreased Tr under subtropical summer conditions due to

increase of heat loss by sensible channels. In Desert rams, Ahmmed and

Abdelatif (1992) reported lower Tr values after shearing. During winter

morning, low Tr values were reported in outbred sheep (Slee et al.,

1988), Suffolk rams (Sano et al. 1995) and Dorset sheep (Entin et al.

1998). However, lower Tr values were reported during summer shearing

in Awassi rams (Younis et al.1975) and Chokla and Nali ewes (Gupta

and Acharya, 1987). Conversely, higher Tr values were reported for

shorn Merino rams (Klemm, 1962), Awassi sheep (Eyal, 1963a) and

Merino sheep (Macfarlane et al., 1966) during summer compared to

values reported to unshorn group; this response was attributed to

penetration of sun rays to the skin surface. However, the high Tr values

reported in shorn Comisana, Barbaresca, Siciliana and Pinzirita sheep

during cold season compared to that reported for the unshorn was

associated with elevation of core temperature which was attributed to an

over-reaction to the mild cold stress resulting from shearing(Piccione et

al.,2002).

In the current results, both unshorn and shorn rams maintained

significantly higher respiration rate (RR) during summer at 7: 00 a.m.

(Table 5.5) and 2:00 p.m. (Table 5.6). This response indicates that both

groups of rams were influenced by the high ambient temperature

prevailing during the experimental period. In unshorn Down cross

wethers (Graham et al., 1959) and Merino wethers (Parer, 1963) in hot

season, the fleece exerts an extra conduction of heat. Elhadi (1988)

reported that in arid areas, the high radiant energy heats up the fleece of

unshorn and skin of shorn sheep which adds to stress produced by high

environmental temperature and enhances evaporative heat loss. High

respiration rate (RR) values were reported during the hot season in shorn

Merino sheep (Klemm, 1962; Macfarlane et al., 1966), Targhee rams

(Hofmeyr et al., 1969) and Najdi rams (Elhadi, 1988). However, in the

present study, shearing of Desert rams during both seasons lowered RR

values at 2: 00 p.m. compared to values reported for unshorn rams. This

low value could be attributed to increased evaporative heat loss from the

skin surface and respiratory tract. Azamel et al. (1987) reported low RR

values in shorn Barki and Barki -Merino cross rams during summer and

attributed this to enhancement of heat loss through the evaporative

channels. Shearing during summer was associated with a significant

decrease in RR of Awassi rams (Younis et al., 1977), Chokla and Nali

ewes (Gupta and Acharya, 1987). However, winter shearing of Suffolk

rams induced a significant decrease in RR (Sano et al., 1995).


The results indicate that certain blood parameters were influenced

by the experimental treatments.Shearing of Desert rams decreased

significantly the PCV level during summer (Table 5.7). This response

could be associated with an increase in water intake, water turnover and

total body water during summer. Macfarlane et al. (1966) reported an

increase in extracellular fluid of shorn Merino sheep in hot environment;

this response was associated with increased respiration rate. Elhadi

(1988) observed significant increases in water turnover and total body

water in summer shorn Najdi rams and this was associated with marked

polypnoea. However, the observations of Ahmed and Abdelatif (1992)

indicate that shearing of Desert rams under mild environmental

conditions induced a slight decrease in PCV level.

The current results revealed that in unshorn rams, the serum

albumin concentration was significantly higher during winter compared

to summer values (Table 5.11). This response could be associated with

increased food intake in the rather cool environment and elevation of the

nutritional status of the animals due to improvement of pasture. Also it

could be related to decrease in water turnover rate and relative

haemoconcentration. A significantly higher serum albumin concentration

was reported in unshorn Desert rams by Ahmed and Abdelatif (1992).

The current results indicate that the shorn rams maintained higher

plasma glucose level in winter compared to the summer value (Table

5.13). This response is most likely related to increase in food intake due

to increase in energy demand for thermogenesis. An increase in voluntary

food intake following shearing at low ambient temperature was reported

in Merino wethers (Minson, 1971) and Suffolk cross ewes (Vipond et al.,

1987). The higher glucose level reported in winter could also be

associated with inhibition of insulin secretion during cold stress.

Symonds et al. (1989) noted higher concentration of glucose level

associated with decreased insulin level in winter shorn ewes. Sano et al.

(1995) reported high glucose concentration in Suffolk rams shorn during

cold conditions, and attributed this response to increased turnover of

blood glucose through gluconeogenesis.


The general patterns indicate that the seminal traits were affected

by season and shearing of Desert rams. A significant reduction in

ejaculate volume was observed in both groups of rams during summer

compared to winter values (Table 5.14). This response indicates that both

groups of rams were influenced by increases in body and scrotal

temperatures which coincided with the prevailing ambient temperature

(Table 5.2) and eventually lowered testosterone secretion beside low food

intake. Waites and Voglmayr (1963) reported low evaporative sweating

in unshorn scrotum of Merino and Border Leicester rams with heating.

However, the authors noted an increase in sweating in shorn scrotum. In

the current study, shearing of Desert rams and their scrota during

summer could have impaired thermoregulation and induced alternations

in accessory genital gland functions and spermatogenesis. Kastelic et al.

(1996) indicated altered scrotal thermoregulation in Merino rams under

heat stress.

The current results indicate that the sperm mass motility (MM) of

both groups of rams was significantly lower during summer compared to

winter values (Table 5.15). This response is clearly associated with

increased scrotal temperature which adversely affects testicular acquired

sperm motility .Similarly summer heat stress significantly lowered sperm

mass motility of Desert rams (Galil and Galil, 1982a) and Chios cross

rams under subtropical conditions (Ibrahim, 1997).

The observations made in the present study also indicate that in

both seasons shearing of rams was associated with decline in sperm

individual motility, IM (Table 5.16). This response could be attributed to

exposure of shorn scrotum to radiant heat from the surrounding or from

the ground while the animals are lying during the experimental period in

winter and summer resulting in increased testicular and epidydimal

temperature during sperms transit and preservation. The prevailing high

ambient temperature and radiant heat may account for the extra heat load

on testes and epididymis .Kastelic et. al (1997) reported that high scrotal

and epididymal temperature interferes with sperm production and

motility.

The data indicate that in both groups of rams the live sperm percent

was significantly lower during summer compared to winter (Table 5.18).

This response is presumably associated with increased body temperature.

Moreover, the increase in radiant heat on shorn testes could increase

testicular temperature and reduce the incidence of live sperms. The

present results are consistent with the findings of Galil and Galil (1982a)

and Alsayed (1996) who reported lower percentage of live sperm in

Desert rams during summer.

The present findings revealed significantly higher abnormal sperm

percent of both groups of rams during summer compared to winter (Table

5.19). This pattern of response indicates the adverse effects of summer

season on semen characteristics. The summer thermal load increased the

incidence of abnormal sperm of unshorn Merino rams (Amir and Volcani,

1965b) and Desert rams (Galil and Galil, 1982a). Heating of the scrotum

increased the percentage of abnormal sperm (Kishore, 1983, Ibrahim et

al., 2001).

5.4.2. Seasonal change, shearing and fasting

The slight reduction in PCV level observed in the present study in

fasted shorn rams during summer compared to unshorn (Table 5.22)

could be associated with increased water intake in hot weather due to

increased evaporative heat loss beside low food intake. Also this response

could be associated with loss of ruminal fluid and slightly increased

extracellular fluid in response to fasting. Hecker et al. (1964) observed

marked reduction in ruminal fluid of fasted Merino and Romney Marsh

ewes in the first two days of the fasting period, which was associated with

expansion of extracellular fluid. Conversely, in fasted Nubian goats (Ali

and Mirghani, 1983) and Murrah buffaloes (Singh and Malik, 1979;

Nangia and Garg, 1988), fasting was associated with high PCV levels; the

authors attributed this response to decline in water consumption and

relative haemoconcen-tration.

The results indicate that fasting influenced the differential

leukocytes count of unshorn and shorn rams. Fasting of shorn rams

significantly reduced the ratio of Lymphocytes during winter compared to

the respective values of unshorn rams (Table 5.24). This response could

be related to suppression of immunity associated with fasting. Walrand et

al. (2001) and Nakamura et al. (2001) noted that in mammals, severe

undernutrition is the main cause of immunodeficiency, as it alters various

hormonal and immune conditions. Prokopenko (1998) indicated that

fasting is associated with reduction in blood level of antiproteolytic

proreins and lipid peroxidase which have an immunosuppressive activity

.However, the adrenal cortex is sensitive to fasting and responds by

diminished activity of lymphocytes (Palmblad et al., 1991). In the current

study, the significantly lower ratio of lymphocytes observed in shorn

rams during summer compared to winter values could be related to the

effects of both fasting and heat stress.

The significantly higher ratio of neutrophils observed in fasted

shorn rams during summer compared to the respective values of unshorn

rams could be associated with heat stress. Heat stress increases the blood

cortisol level and induces vasodilatation. Mitchell et al. (2000) and

Ganong (2003) indicated that cortisol activates immune system during

stress conditions. In the present study, although shorn rams were exposed

to heat stress, both groups revealed high ratio of neutrophils during

summer compared to winter.

In unshorn rams, the significantly higher ratio of neutrophils

reported post-fasting during winter could be attributed to the effects of

cold conditions. Mitchell et al. (2000) indicated that an increase in

neutrophils ratio during cold exposure is attributed to increased

mobilization from internal organs.

The significantly higher ratio of eosinophils observed post-fasting

for both groups of rams during summer could be attributed to the effects

of adrenal glands hyperactivity. Under stress conditions, cortisol secretion

increased, resulting in increased ratio of eosinophils of mice (Komori et

al., 1996).

The significant reduction in monocytes ratio in both seasons post-

fasting in unshorn rams compared to the respective values obtained for

the shorn rams (Table 5-24) could be related to the low water intake

associated with food deprivation. Barbour et al. (2004) reported

suppression of immune system in response to water deprivation in Awassi

fat – tailed sheep.

In the current results, the serum total protein level was significantly

higher during winter in fasted shorn rams compared to values obtained

for unshorn rams (Table 5.25). This response could be related to high

food intake in shorn rams before fasting coupled with nitrogen

retension. Sano et al. (1995) noted a positive protein retension in shorn

Suffolk rams at the expense of an enhancement of non- protein oxidation

during exposure to cold. However, the low total protein level of fasted

unshorn rams observed during winter compared to summer could be

attributed to loss of body protein reserve for vital processes during winter

fasting. Panaretto (1964) observed a gradual depletion of protein and fat

of body reserve in starved Boarder Leicester and Merino ewes.

The significantly higher albumin concentration observed in

unshorn rams post-fasting during summer compared to winter (Table

5.26) could be related to low water intake and haemoconcentration , in

addition to the continuous mobilization of body protein due to fasting.

Sasaki et al. (1974) reported high albumin concentration in Japanese

Corriedale wethers during fasting and attributed this to increased

mobilization of tissue protein. However, Naqvi and Rai (1988) reported

no significant influences of fasting in serum albumin concentration in

Avivastra ewes.

In the current results, the serum urea concentration was

significantly higher in shorn rams post-fasting during winter compared to

the value obtained for the unshorn (Table 5.27). This could be related to

the improvement of nutritional status before fasting. Also it could be

associated with increased blood concentration of urea and amino acids

nitrogen associated with low water intake resulting in

haemoconcentration. Eisemann and Nienaber (1990) reported that in

fasted ruminants, increased blood concentration of urea – nitrogen and

amino acids nitrogen was observed, in addition to a decrease in uptake of

ammonia by liver. However, the low level of serum urea observed post-

fasting during both seasons in unshorn rams and during winter in shorn

rams compared to summer values could be associated with increased

protein breakdown and urinary urea excretion. Burrin et al. (1989a,b)

indicated that fasting metabolism increases urinary nitrogen excretion in

ruminants indicating protein oxidation due to glucose deficiency.

However, the low urea level reported post- fasting during summer could

also be related to low fermentation capacity of rumen during exposure to

hot environment. Hutcheson and Cole (1986) reported low production of

urea in cattle in hot environment and attributed this response to low food

consumption and reduced rumen movement. Similarly, Leibholze (1970)

reported greater urinary urea excretion in fasted cross bred wethers.

In the current results, the plasma glucose level of shorn rams was

significantly higher post-fasting in both seasons compared to values

obtained for unshorn (Table 5.28). This response could be associated with

increased gluconeogenesis associated with increased adrenaline secretion.

Murray et al. (1990a) reported high glucose concentration in fasted

Spanish does due to gluconeogenesis. However, the significantly lower

plasma glucose level observed in fasted unshorn rams during summer

compared to winter values could be related to low ruminal activity in hot

environment and consequently low production of propionate. Johnson et

al. (1969) noted low production of volatile fatty acids (VFAs) in rumen

during hot environment due to low food consumption. Also this reduction

in glucose concentration could be associated with increased ruminal pH

during heat stress. In ruminants, on exposure to heat stress , ruminal

fermentation decreased and the pH increased (Hutcheson and Cole,

1986). Increased ruminal pH above 6.0, the optimum value for bacteria

producing propionic acid, reduces its concentration and consequently

lowers blood glucose level (Hara et al., 2002). However, the significantly

lower plasma glucose level post-fasting during winter in shorn rams

compared to the respective summer value could be related to increased

secretion of glucocorticoids. Sasaki et al. (1974) reported low blood

glucose level in fasted Japanese Correidale wethers which was attributed

to delayed gluconeogenesis in response to the action of glucocorticolds

with the continuous absorption of of glucose from rumen.

5.5. Summary

1. Eight Desert rams were used to investigate the effects of season

and shearing on thermoregulation blood composition and seminal

traits. The effects of fasting on blood constituents were also

examined

2. The rectal temperature (Tr) value at 7: 00 a.m. was significantly

lower in shorn rams in both seasons. Shearing during summer

significantly decreased Tr at 2:00 p.m. compared to values reported

for unshorn rams. In both seasons, shearing significantly decreased

RR at 2: 00 p.m.

3. The PCV level of shorn rams was significantly lower during

summer compared to winter values.

4. Fasting of shorn rams significantly lowered the ratio of

lymphocytes during winter compared to value reported for unshorn

rams. The ratio of lymphocytes of fasted shorn rams was

significantly lower during summer compared to winter values.

Fasting significantly increased the ratio of neutrophils during both

seasons in unshorn rams. During summer, the ratio of neutrophils

of fasted shorn rams was significantly higher compared to winter

values.The ratio of eosinophils was significantly higher during

summer in both groups of rams post – fasting compared to winter

values. The post–fasting value of monocytes ratio was significantly

lower in both seasons in unshorn rams. The post–fasting ratio of

monocytes of shorn rams was significantly lower in summer

compared to winter values.

5. Shearing significantly increased serum total protein level post-

fasting during winter compared to values obtained for unshorn

rams. The total protein level in fasted shorn rams was significantly

higher during winter compared to summer values. Serum albumin

level of fasted unshorn rams was significantly higher during

summer compared to the respective winter values. Serum urea

concentration was significantly higher during winter in fasted

shorn rams compared to values reported for unshorn. Post-fasting

serum urea concentration was significantly lower in unshorn rams

during both seasons. The post – fasting value of serum urea

concentration of shorn rams was significantly lower during

summer compared to winter value.

6. Shearing significantly increased plasma glucose level during winter

compared to values reported for unshorn. The glucose level was

significantly higher during winter compared to summer value in

shorn rams. Post-fasting, shorn rams maintained significantly

higher plasma glucose level in both seasons compared to values

obtained for the unshorn rams. The glucose level of fasted unshorn

rams was significantly lower during summer compared to the

respective winter value. In shorn rams, the plasma glucose level

was significantly lower post-fasting during winter compared to

summer value.

7. The ejaculate volume of both groups was significantly lower

during summer compared to winter values. Shearing did not

significantly influence the ejaculate volume.

8. During summer, the sperm mass motility (MM) was significantly

lower in shorn rams compared to values of unshorn rams. For both

unshorn and shorn rams, the MM was significantly lower in

summer compared to respective winter values. The sperm

individual motility (IM) was significantly lower in shorn rams in

both seasons. For unshorn rams, the sperm IM was significantly

lower in summer compared to winter values.

9. In both groups of rams, the live sperm percent was significantly

lower compared to respective winter values. In both groups of

rams, the abnormal sperm percent was significantly higher during

summer compared to winter values.

CHAPTER SIX

GENERAL DISCUSSION AND CONCLUSIONS

Under tropical conditions of arid and semi-arid range lands of

Sudan, the indigenous sheep breeds may suffer from harsh environmental

conditions which include thermal stress and shortage of food. During dry

season, low rainfall associated with poor pastures and high solar heat load

may influence the physiological responses of sheep and hamper their

productivity.

The studies described in this thesis investigated the effects of

lowering the feeding level of lucerne hay and seasonal changes in thermal

environment on thermoregulation, blood metabolites and semen

characteristics of Desert rams (Chapter 3). The effects of exposure to

solar radiation on thermoregulation, blood composition and semen

characteristics and the combined effects of exposure to solar radiation and

exhaustion test on blood composition and semen characteristics were also

examined (Chapter 4). The responses of Desert rams to shearing and

seasonal changes in thermal environment on thermoregulation, blood

composition and seminal traits, and the effects of shearing, season and

fasting on blood composition were also evaluated (Chapter 5).

Feeding lucerne hay below maintenance level lowered BW (Table

3.3) irrespective of season, which was associated with reduced scrotal

circumference (Table 3.4). This response indicates that during the dry

season and scarce forage, grazing Desert rams are likely to be subjected

to loss of BW. Furthermore, walking in pursuit of pasture raises the

energy demand. The reduced scrotal circumference associated with feed

restriction indicates that poor pasture during growth impacts on ram

lambs in delaying the age of puberty. For mature Desert rams, the

availability of good pasture is an important factor for their reproductive

efficiency as a decrease in scrotal circumference is usually associated

with reduced number of seminiferous tubules (Jainudeen and Hafez,

2000). Harvey (1995) noted that food availability is a major factor

regulating somatic axis and reproductive performance in mammals. It can

be postulated that in Desert rams, summer season is mostly considered as

the harsh period for scarcity of food and lack of water. To withstand this

nutritional stress , animals should be given dietary supplementation and

previously well fed .

The studies revealed that underfed Desert rams had low rectal

temperature, Tr (Tables 3.5, 3.6) in both seasons, a response that was

attributed to decline in metabolic rate. During summer, irrespective of the

nutritional status, all rams suffered from heat stress which was reflected

in higher Tr (Table 3.6). Also continuous exposure of the Desert rams to

solar radiation increased heat gain and raised the body temperature

(Tables 4-3, 4-4). These findings indicate that when rams are kept under

direct solar radiation during grazing, hyperthermia in addition to internal

heat production associated with feeding, and muscular activity when

searching for food and water, result in increased body temperature and

alteration in general physiological responses.

During both seasons, Tr of Desert rams was lowered by shearing

(Tables 5.3, 5.4). However, the increase in body temperature of Desert

rams observed during summer in all experiments and during exposure to

solar radiation were offset by enhancement of the cooling mechanism,

through an increase in RR (Tables 4.5, 4.6) and a decrease in exrernal

insulation by shearing (Table 5-6). Previous studies indicated that

shearing of Desert rams alleviated thermal stress as it was associated

with decrease in body temperature and respiratory frequency (Ahmed and

Abdelatif, 1992).

The studies have indicated that the blood constituents were

influenced by the experimental treatments. In shorn Desert rams, the low

PCV level (Table 5.7) could have been associated with changes in the

water relations of Desert rams in response to stimulation of the

thermoregulatory centre in the hypothalamus and to maintain appropriate

osmolatity in body fluids. Similar results representing changes in body

fluids were reported in shorn Desert rams (Elhadi, 1988). The low PCV

level reported in exhausted heat-stressed Desert rams (Table 4.23)

indicates that frequent mating of rams and increased muscular activity

and consequent increase in oxygen consumption by muscles exerted an

additional stress superimposed on the influences of heat exposure.

The immune system of animals is influenced by various stressful

conditions. The results indicated that exposure to solar radiation

influenced the leukocytic profile in rams (Table 4.9), decreases in the

ratio of eosinophils and neutrophils were attributed to their sequestration

in response to an increase in secretion of glucocorticoids. Ganong (2003)

suggested that in humans, low ratios of eosinophils could be related to

sequestration in the spleen and lung due to excessive secretion of cortisol.

Also the increase in the ratio of monocytes indicates adrenal gland

hyperactivity. The low TLC of exhausted unshaded Desert rams (Table 4-

25) was attributed to the migration of leukocytes to active muscles.

Fasting of shorn Desert rams (Table 5.24) was associated with low ratio

of lymphocytes in both seasons, which could be attributed to the effect of

increased secretions of glucocorticoides. Ganong (2003) indicated an

increase in destruction of lymphocytes due to increased glucocorticoids in

stressful conditions. During summer, Desert rams revealed high ratios of

neutrophils and eosinophils. This response could be related to increased

extravascular fluid and migration of these cells from the marginal pool to

the tissues.

The studies also revealed changes in blood metabolites of Desert

rams on exposure to various stressful conditions. Feed restriction

decreased serum total protein level of Desert rams during winter (Table

3.9) and serum albumin level in both seasons (Table 3.10). These

responses are attributed to low protein intake and reduction in ruminal

synthesis of proteins. McDonald et al (2002) indicated that ruminants

depend on food protein escaping ruminal degradation and protein

synthesized by rumen microbes.

Exposure to solar radiation increased the level of serum total

protein (Table 4.10) which was attributed to excessive protein production

from body reserve during heat stress. In ruminants, heat stress causes

mobilization of protein from the tissue to the plasma to be catabolised in

the liver (Kamal and Shebaita, 1972). However, serum albumin

concentration decreased in response to heat stress (Table 4.11). This was

clearly related to low food intake in addition to increased water

consumption for increasd evaporative heat loss which resulted in

haemodilution. The low urea concentration observed during exposure of

Desert rams to solar radiation (Table 4.12) could be associated with low

ruminal activity and production of urea, in addition to increased urinary

excretion and haemodilution due to increased water intake during heat

stress. In ruminants, an increased water intake is usually associated with

haemodilution and increases in urinary excretion of urea (Cheeke,

2005a).

The studies indicated that carbohydrate metabolism was affected

by the experimental treatments. The significantly lower plasma glucose

level in response to exposure to solar radiation (Table 4.13) was

attributed to low food intake. However, in exhausted unshaded Desert

rams, the significantly lower plasma glucose level reported (Table 4.35)

was related to low food intake in addition to increased demand of glucose

for increased muscular movement during electro-ejaculation. The

significant decrease in glucose level of shorn Desert rams during summer

(Table 5.13) could have been associated with decreased thyroid

stimulation. Dauncey (1990) and McDonlad et al. (2002) indicated that

exposure of ruminants to cold environment increased thyroid hormone

metabolism. The higher glucose level of shorn rams in winter is likely to

be related to availability of pasture and increased food intake. Previous

studies reported increased dry matter intake and body weight gain in

shorn Desert rams during mild winter conditions (Ahmed and Abdelatif,

1992). However, in the current studies, winter fasting of shorn Desert

rams increased plasma glucose level comared to the respective group

(Table 5.28).This response is attributed to increased gluconeogenesis

during food deprivation for vital body processes, while the reduction in

plasma glucose level during winter compared to summer is related to

increased demand for thermogenesis. Brockman and Laarveld (1986)

indicated that shifts in energy metabolism occur during fasting as

nutrients are metabolized from peripheral stores. Moreover, the reduction

in blood glucose during fasting is compensated by endogenous glycogen

(Naqvi and Rai, 1988).

The studies reported in this thesis indicate that the plane of

nutrition and circannual changes in tropical thermal environment

influenced the seminal traits in Desert rams. The high thermal load

encountered during summer constituted the major stressful factor which

influenced semen characteristics superimposed by feed restriction and

shearing. Prolonged exposure of the Desert rams to direct solar radiation

in the tropics during the hot season adversely affects semen

characteristics.

The restriction of food intake significantly lowered the ejaculate

volume in both seasons and the values reported during summer were

lowest (Table 3.13). This response is attributed to reduced secretion of

LH and testosterone as well as the activities of androgen–dependent

organs. This result indicates that during drought conditions or food

scarcity the reduction in ejaculate volume of Desert rams is reflected in

reduced serving capacity. Previous studies on Merino rams reported that

feed restriction was associated with low ejaculate volume (Martin and

Walkden-Brown, 1995). Prolonged exposure of Desert rams to solar

radiation resulted in low ejaculate volume (Table 4.14). This observation

indicates that exposure of Desert rams to direct solar radiation in the

tropical environment may have influences on testicular tissues and it

generally increases body temperature which alters testicular function due

to inhibition of hypothalamic hormonal functions.

The studies indicated that frequent ejaculation of unshaded Desert

rams 4–6 times/day for 3 successive days reduced the ejaculate volume

(Table 4.36). This is related to continuous withdrawal of epididymal

reserve, in addition to reduced secretions of accessory genital glands.

These findings indicate that in Desert rams, during exposure to solar

radiation under extensive husbandry conditions in the tropical

environment, frequent ejaculation will lower the serving capacity of rams.

The motility of spermatozoa was influenced by experimental

nutritional and thermal treatments. Lowering the level of feeding reduced

sperm mass motility (MM) of Desert rams (Table 3.14). This response is

attributed to a decrease in nutritive materials of seminal plasma necessary

for sperm motility, which are derived from blood metabolites. However,

this response was aggravated by hot summer conditions as a result of

increase in the metabolic rate of spermatozoa. The MM of spermatozoa

was also reduced on exposure of rams to solar radiation (Table 4.15).

This was clearly associated with impairment of testicular

thermoregulation. Previous studies indicated that unshaded Suffolk rams

had low MM (Marai et al., 2003). The sperm individual motility was also

affected by the treatments, it showed a significant decline in response to

feed restriction irrespective of season (Table 3.15), which denotes the role

of epididymal secretions as sperms acquire motility in their epididymal

transit. This observation indicates that during the dry season, poor

pastures will influence the sperm motility and fertilizing capacity of

ejaculate as individual motility of sperms is a major factor for ova

fertilization. Frequent ejaculation of unshaded rams revealed lower sperm

individual motility (Table 4.41). Kaya et al. (2002) reported low sperm

individual motility in Konya Merino rams when frequently ejaculated.

Shearing of Desert rams during summer and winter was associated with a

reduction in sperm individual motility (Table 5-16). This result indicates

that the hazard of exposure of shorn scrotum to summer and winter sun

lowers its thermoregulatory efficiency.

The significant lowering of sperm cell concentration in response to

feed restriction of Desert rams in both seasons (Table 3-16) was

associated with reduced scrotal circumference observed in the studies,

which indicates reduced number of seminiferous tubules and

consequently sperm production. The sperm cell concentration was also

reduced when Desert rams were exposed to solar radiation (Table 4.17),

which could be related to testicular degeneration in response to thermal

stress. Jainudeen and Hafez (2000) indicated that increasing scrotal

temperature lead to testicular degeneration. Frequent ejaculation of

unshaded Desert rams lowered sperm cell concentration (Table 4.43); this

was attributed to low number of sperm produced and continuous

evacuation of epididymal tail. Galil et al. (1984) reported low sperm

concentration in Najdi rams after frequent ejaculation.

The reduction in live sperm percent in response to feed restriction

during summer (Table 3.17) was attributed to less nutritive materials

necessary for intact membrane coupled with summer heat load. However,

the decline in the percentage of live sperms reported during exposure of

Desert rams to solar radiation (Table 4.18) is clearly associated with

increased number of dead sperms due to increased testicular temperature.

Frequent ejaculation of unshaded Desert rams increased the percentage of

live sperms in the last two days compared to the initial value (Table

4.45), indicating removal of dead sperms that resulted from exposure to

solar radiation.

The percentage of abnormal sperm was significantly higher in

response to feed restriction during summer (Table 3.18). Also exposure

of Desert rams to solar radiation increased the incidence of abnormal

sperms (Table 4.19) due to damage in stages of spermatogenic cycle and

inadequate epididymal maturation. Ibrahim et al., (2001) reported an

increase in abnormal sperms incidence in Montedale cross Texel rams

when their scrota were heated. However, frequent ejaculation reduced the

abnormal sperm percent (Table 4.47) of unshaded Desert rams, which

was induced by exposure to heat stress.

The effects of feed restriction, seasonal changes in thermal

environment, exposure to solar radiation and exhaustion test and shearing

on semen characteristics were investigated in the studies. Further studies

are needed to evaluate the effects of these factors on biochemical,

histochemical and histological characteristics of testicular tissues and

seminal plasma in the tropics. Future studies should also assess the effects

of nutritional and environmental factors on the hypothalamo–pituitary–

testicular axis and endocrine responses. Evaluation of the fertilizing

capacity of ejaculates collected from Desert rams exposed to nutritional

and environmental stress will verify their reproductive efficiency.

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بسم اهللا الرحمن الرحيم

األطروحةة صالخ

على تنظيم ية والبيئيةائالغذالعوامل بعض استقصاء تأثيرات الدراسة الى تهدف هذه

وخصائص blood composition، مكونات الدم thermoregulation درجة حرارة الجسم

تقييم على ارب اشتملت التج. في الكباش الصحراوية semen characteristicsالسائل المنوي

من المعدل العادي في فصلي % 33و % 66خفض مستوى التغذية بالبرسيم الجاف تأثير

. مؤيضات الدم وخصائص السائل المنى، واثر ذلك على التنظيم الحراري للجسمالصيف والشتاء

على للكباش exhaution test التعرض ألشعة الشمس واإلجهاد الجنسي آما تمت دراسة اثر

خفض أيضا تمت دراسة اثر . مكونات الدم وخصائص السائل المنوي، م الحراري للجسمالتنظي

على االستجابات في فصلي الصيف والشتاء shearing and fasting والصومغطاء الصوف

. الفسيولوجية

للكباش في فصلي الصيف % 33أدي تخفيض مستوى التغذية من المعدل العادي بنسبة

إنخفضت درجات حرارة الجسم في . ض في وزن الجسم ومحيط الخصيتينوالشتاء إلى إنخفا

آما إنخفض معدل التنفس ،الصباح والظهيرة وآان هنالك فرق واضح بين الدرجتين أثناء النهار

أما ترآيز البروتين الكلي في السيرم فقد إنخفض في فصل الشتاء فقط إستجابة .في فترة الصباح

خفض . إنخفض ترآيز األلبيومين في فصلي الشتاء والصيف معًالخفض مستوى التغذية بينما

مستوى التغذية في الكباش أدى إلى إنخفاض في حجم السائل المنوي، الحرآة الفردية للنطاق

في ها من ونسبة الحي فوترآيزها في فصلي الصيف والشتاء بينما إنخفضت الحرآة الكلية للنطا

وآانت خصائص .طبيعية الشكل في فصل الصيف فقط الغير فوزادت نسبة النطافصل الصيف

.السائل المنوي أقل مستوى في فصل الصيف عنها في فصل الشتاء

في أدى تعرض الكباش ألشعة الشمس إلى إرتفاع درجة حرارة الجسم في الصباح

التنفس معدل ارتفعبينما األول اإلسبوع فىظهيرةال و فى فترة الثاني من فترة التجربةاألسبوع

بالنسبة إلى مكونات الدم فقط إنخفضت .في الصباح والظهيرة في اإلسبوع األخير من التجربة

في اإلسبوعين األخيرين من تعرض الكباش ألشعة الشمس neutrophilsنسبة الكريات المتعادلة

إنخفضت نسبة الكريات الحمضيةو monocytesزادت نسبة الكريات األحادية بينما

eosinophils آيز البروتين رتآان فقد مقارنة بقيم الكباش التي في الظل في اإلسبوع األخير

بينما انخفض ترآيز األلبيومين في . من فترة التجربةلث اإلسبوع الثافيأعلي الكلي في السيرم

1

السيرم في االسبوع الثاني وانخفض ترآيز اليوريا ي السيرم وجلكوز البالزما في االسبوع

. الثالث من التجربة

إنعكس أثر التعرض ألشعة الشمس على خصائص السائل المنوي في خفض آل من

يز النطاف ونسبة الحي منها، بينما حجم السائل المنوي، الحرآة الكلية والفردية للنطاف، ترآ

اإلجهاد الجنسي للكباش لمدة ثالثة أيام متتالية .زادت نسبة النطاف ذات األشكال غير الطبيعية

في اليوم األخير والعدد الكلي PCVخالل تعرضها ألشعة الشمس أدي إلى خفض مكداس الدم

األول والثاني في اليومآيز البروتينلكريات الدم البيضاء في اليوم األول آما أدي إلى خفض تر

نسبة الحرآة الفردية للنطاف، انخفضت. في اليوم الثاني وزاد ترآيز جلكوز البالزماللتجربة

لإلجهاد الجنسي والتعرض ألشعة استجابةها مناألشكال الغير طبيعية ونسبة ترآيز النطاف

اد الجنسي للكباش التي في الظل إلى أدي اإلجه. بينما زادت نسبة الحي من النطاف معاالشمس

وعدد في اليوم األول والثاني TLC الدم والعدد الكلي لكريات إلى ثالثة أيام خفض مكداس الدم

في آما أدي أيضًا إلى خفض ترآيز البروتين الكلي في السيرم في اليوم األول الكريات األحادية

في وجلوآوز البالزمافي اليوم األخير ولينا وزيادة ترآيز الباليوم األول والثاني من التجربة

أدي إلى خفض حجم للكباش التي في الظل اإلجهاد الجنسي. اليوم األول واألخير من التجربة

في ، ترآيزها في اليوم األول والثالث، الحرآة الفردية للنطاف في األيام الثالث السائل المنوي

. في اليوم الثانيغير طبيعيةوزيادة نسبة النطاف الاليوم األول والثاني

خفض غطاء الصوف في الكباش الصحراوية أدي إلى خفض درجة حرارة الجسم

بينما إنخفض معدل . صباحًا في فصل الشتاء والصيف وفي الظهيرة في فصل الصيف فقط

فى بالنسبة لمكونات الدم فقد أدى إزالة الصوف من الكباش.التنفس في الظهيرة في الفصلين

أدى خفض غطاء . مقارنة بقيم الصيف نسبة ترآيز جلكوز البالزماارتفاع في الى فصل الشتاء

الصوف في الكباش إلى إنخفاض في الحرآة الكلية للنطاف صيفًا والفردية في فصلي الشتاء

مقارنة مع القيم المتحصل عليها في الكباش آاملة غطاء الصوف فقد إنخفض عدد . والصيف

فصلي إستجابة لخفض غطاء الصوف ومنع الغذاء في lymphocytes لليمفاويةالكريات ا

أدى الصوم إلى زيادة نسبة . الصيففي بينما زادت نسبة الكريات المتعادلةوالصيف الشتاء

آريات الدم المتعادلة في الحيوانات ذات الصوف ومنخفضة الصوف في فصل الصيف

البروتين الكلي في آل من إرتفع ترآيز. monocytesآريات الدم األحادية نسبة وانخفضت

رآيزت السيرم والبولينا في الشتاء إستجابة لمنع الغذاء وخفض غطاء الصوف بينما إنخفض

وارتفع ترآيز جلكوز البالزما في الصيف والشتاء مقارنة مع قيم حيوانات .البولينا في الصيف

2

في حيوانات الظل . لشتاء مقارنة مع قيم الصيفبينما انخفض ترآيز جلوآوز البالزما في االظل

أدى الصوم إلى زيادة نسبة آريات الدم المتعادلة والحمضية في فصل الصيف وخفضت نسبة

الكريات األحادية في فصلي الصيف والشتاء، آما أدى الصوم إلى زيادة مستوى ألبيومين السيرم

يف والشتاء وجلوآوز البالزما في بولينا السيرم في فصلي الصخفض ترآيز في فصل الصيف

. فصل الصيف

نتائج هذه الدراسة أوضحت أن خفض مستوى الغذاء أدى إلى حدوث تغييرات إيجابية

أيضا أوضحت الدراسة إن للكباش الصحراوية . في االستجابات الفسيولوجية للضأن الصحراوي

يؤثر سلبا على التنظيم اد الحراري اإلجه. المقدرة على التأقلم في حالة تعرضها ألشعة الشمس

اإلجهاد الجنسي مع تعرض الكباش .السائل المنويخصائص الحراري لكيس الصفن وبالتالي

إزالة غطاء الصوف صيفا . الصحراوية ألشعة الشمس لم يكن له إي اثر إجهادي إضافي عليها

ها األثر السلبي على ن لأثر اإليجابي على عملية التنظيم الحراري للجسم بينما آاله وشتاء

.حرآة النطاف

3

effects of nutritional and environmental factors on physiological responses and semen...

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