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EFFECT OF EJACULATION FREQUENCY AND
MANAGEMENT CONDITIONS ON SEMEN QUALITY,
FERTILITY AND HATCHABILITY OF LOCAL
TURKEYS IN THE HUMID TROPICS
BY
EZIKE, JOHNSON CHUKWUMA
PG/M.SC/06/42146
SUPERVISOR: PROF. S. O. C.UGWU
DECEMBER, 2010
EFFECT OF EJACULATION FREQUENCY AND
MANAGEMENT CONDITIONS ON SEMEN QUALITY,
FERTILITY AND HATCHABILITY OF LOCAL
TURKEYS IN THE HUMID TROPICS
BY
EZIKE, JOHNSON CHUKWUMA
PG/M.SC/06/42146
A THESIS PRESENTED TO THE DEPARTMENT OF ANIMAL
SCIENCE, UNIVERSITY OF NIGERIA, NSUKKA IN PARTIAL
FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD
OF M.Sc DEGREE IN ANIMAL REPRODUCTIVE PHYSIOLOGY
DECEMBER, 2010
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ii
CERTIFICATION
I certify that this research work was duly carried out by Mr. Ezike,
Johnson C. in the Department of Animal Science, Faculty of Agriculture,
University of Nigeria, Nsukka as part of the requirements for the award of
Master of Science Degree in Animal Reproductive Physiology
_____________________ ______ ___________________ _____
DR. A.E. ONYIMONYI DAT PROF. S.O.C. UGWU DATE
HEAD OF DEPARTMENT PROJECT SUPERVISOR
______________________ ________
PROF. B.N. MARIRE Date
EXTERNAL EXAMINER
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ACKNOWLEDGEMENT
I thank God for the gift of life and good health throughout the period of
this work. Words are inadequate to convey my profound gratitude to my
Project Supervisor, Prof. S.O.C. Ugwu, for his fatherly and invaluable support
throughout the period of this work.
I am indebted to Engr. Oti Stephen, Sir Elijah Taagbo Ugwu and
Ogbonna Emmanuel for their financial support.
I appreciate the support of Prof. Ezekwe, A.G., Dr. Machebe, S.N., Mr.
Ozioko Mark, Amoke Anenechukwu, Ugwu Cosmas, Asadu Nichodemous and
a host of other friends whose contributions made this work a success.
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TABLE OF CONTENTS
Title page------------------------------------------------------------------------- i
Certification--------------------------------------------------------------- ii
Acknowledgement-------------------------------------------------------------- iii
Table of contents---------------------------------------------------------------- iv
CHAPTER ONE: INTRODUCTION
1.1Background of the Study ---------------------------------------------------- 1
1.2 Statement of the Problem -------------------------------------------------- 5
1.3 Objective of the Study ------------------------------------------------------ 5
1.4 Justification of the Study --------------------------------------------------- 6
CHAPTER TWO: LTERATURE REVIEW
2.1 Anatomy of the reproductive system of the Tom ----------------------- 8
2.2 Spermatogenesis in Toms -------------------------------------------------- 9
2.3 Factors that affect Semen Production ------------------------------------- 12
2.3.1 Ambient Temperature ---------------------------------------------------- 13
2.3.2 Photoperiod or daylight length ------------------------------------------ 13
2.3.3 Nutrition -------------------------------------------------------------------- 15
2.3.4 Age -------------------------------------------------------------------------- 15
2.3.5 Breed/Species Variation -------------------------------------------------- 16
2.4 Semen Collection Techniques --------------------------------------------- 16
2.4.1 Handling male turkeys for collection of Quality Semen ------------ 16
2.5 Frequency of Semen Collection in Turkeys ----------------------------- 18
2.5.1 Factors Affecting post-ejaculation Semen Quality ----------- 20
2.5.2 Ambient temperature ----------------------------------------------------- 20
2.5.3 Semen Osmotic Pressure ------------------------------------------------- 21
2.5.4 Semen PH ------------------------------------------------------------------ 21
2.5.5 Concentration of sperm in ejaculate ------------------------------------ 21
2.5.7 Gases ------------------------------------------------------------------------ 22
2.5.8 Bacterial Contaminants -------------------------------------------------- 22
2.6. Semen Quality Evaluation ------------------------------------------------- 22
2.6.1 Semen Colour -------------------------------------------------------------- 24
2.6.2 Semen Volumes ----------------------------------------------------------- 25
2.6.3 Motility -------------------------------------------------------------------- 27
2.6.4 Sperm Concentration ----------------------------------------------------- 33
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2.6.5 Normal and Abnormal Sperm ------------------------------------------- 35
2.6.6 Live Dead Sperm --------------------------------------------------------- 36
2.7 Biochemical Parameters ---------------------------------------------------- 36
2.8 Basic Anatomy and physiology of the Hen‟s Reproductive Tract ---- 38
2.8.1 Sperm Storage in Vivo --------------------------------------------------- 41
2.8.2 Behaviour of Sperm in the Oviduct of the Hen ----------------------- 41
2.9 Artificial Insemination in Turkeys ---------------------------------------- 43
2.9.1 Artificial Insemination Techniques in Turkeys ----------------------- 45
2.9.2 Advantages of Artificial Insemination -------------------------------- 46
2.9.3 Depths and Time of Insemination -------------------------------------- 47
2.10 Fertility in Turkeys -------------------------------------------------------- 48
2.10.1 Infertility in Turkeys ---------------------------------------------------- 49
2.10.2 Factors that Affect Fertility in Turkeys Hens ------------------------ 49
2.10.2.1 Factors influencing infertility in naturally mated hens ----------- 50
2.10.2.2 Infertility Syndrome -------------------------------------------------- 50
2.10.2.3 Age of the Hen --------------------------------------------------------- 51
2.10.2.4 Mating Behaviour in Turkey Hens --------------------------------- 51
2.10.2.5 Effects of Body Weight of the Hen --------------------------------- 53
2.10.2.6 Nutritional Causes of Infertility ------------------------------------ 53
2.10.2.7 Influence of Disease on Fertility ----------------------------------- 54
2.11.1 Infertility under Artificial Insemination ----------------------------- 54
2.11.2 Stress --------------------------------------------------------------------- 54
2.11.3 Oviductal Environment of the Hen ------------------------------------ 55
2.11.4 Immunity against Sperm ------------------------------------------------ 55
2.11.5 Semen Quality ----------------------------------------------------------- 56
2.11.6 Number of sperm inseminated into the oviduct -------------------- 56
2.11.7 Time of Insemination --------------------------------------------------- 57
2.12.1 Infertility in Males ------------------------------------------------------ 58
2.12.2 Body weight of Toms -------------------------------------------------- 58
2.12.3 Age ----------------------------------------------------------------------- 59
2.12.4 Male Mating Behaviour ----------------------------------------------- 59
2.13 Hatchability in Turkeys --------------------------------------------------- 61
2.13.1 Influence of temperature on Hatchability ---------------------------- 62
2.13.2 Relative Humidity ------------------------------------------------------ 63
2.13.3. Egg Shell Characteristics --------------------------------------------- 63
2.13.4 Disease/Egg Contamination ------------------------------------------- 64
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2.13.5 Egg Storage -------------------------------------------------------------- 64
2.13.6 Nutrition ------------------------------------------------------------------ 65
2.13.7 Age of Hens ------------------------------------------------------------- 65
2.13.8 Incubator setting and peculiar egg characteristics ------------------ 65
2.13.9 Genetic factors affecting hatchability -------------------------------- 66
2.14 Candling and egg breakout ---------------------------------------------- 67
2.15 Systems of turkey management ----------------------------------------- 68
2.15.1 Rearing systems in turkey production -------------------------------- 69
2.15.2 Semi-intensive management system --------------------------------- 69
2.15.1 Nutritional management under semi-intensive system ------------- 71
2.16 Intensive management system ------------------------------------------- 72
2.16.1 Nutritional management of turkey under intensive system -------- 73
2.16.2 Vitamins and minerals requirements of turkeys --------------------- 76
2.16.3 Minerals ------------------------------------------------------------------ 77
CHAPTER THREE: MATERIALS AND METHOD
3.1 Location of the Study ------------------------------------------------------- 79
3.2 Plan of the Study ------------------------------------------------------------ 79
3.3 Duration of the Study ------------------------------------------------------- 80
3.4 Procurement and management of experimental animals -------------- 81
3.5 Pre-experimental Period/training of toms for semen collection ------ 83
3.6 Data collection: experiment I (Physical examination of semen) ------ 83
3.7 Semen quality parameters measured -------------------------------------- 84
3.7.1 Volume --------------------------------------------------------------------- 84
3.7.2 Progressive motility ------------------------------------------------------ 84
3.7.3 Live, Normal and Abnormal Spermatozoa --------------------------- 85
3.7.4 Sperm concentration ------------------------------------------------------ 85
3.8 Experiment 2: Artificial insemination, fertility and hatchability
Trials --------------------------------------------------------------------------- 86
3.9 Egg collection, candling and hatching ------------------------------------ 89
3.10. Statistical analysis -------------------------------------------------------- 90
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CHAPTER FOUR: RESULTS AND DISCUSSION -------------------- 91
CHAPTER FIVE: CONCLUSION AND RECOMMENDATIONS
CONCLUSION --------------------------------------- 114
Recommendation ---------------------------------------------------------------- 116
References ------------------------------------------------------------------------ 117
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LISTS OF TABLES
Table 1: Effects of age and photoperiod on weekly sperm output of
toms ( x + SE). ----------------------------------------------------------- 14
Table 2: Daily sperm output of turkeys subjected to various frequencies
of semen collection ( x + SE) ------------------------------------------ 20
Table 3: Semen volume of toms subjected to three frequencies of
semen collection. -------------------------------------------------------- 26
Table 4 Semen volume of tomes subjected to seven frequencies of
semen collections -------------------------------------------------------- 26
Table 5:Description of motility grades in farm animals/based
on scoring method -------------------------------------------------------- 31
Table 6: Sperm motility (%) of toms subjected to various frequencies of
semen collection --------------------------------------------------------- 32
Table 7: Mean percentage sperm motility of toms subjected to
various frequencies of semen collection ----------------------------- 32
Table 8: Sperm conc. of toms subjected to three frequencies of
semen collection. -------------------------------------------------------- 34
Table 9: Sperm concentration of toms subjected to various
frequencies of semen collection ( x + S E) --------------------------- 34
Table 10: Recommended nutrient allowance for poultry under tropical
climatic condition -------------------------------------------------------- 73
Table 11: Semen quality parameters of local turkeys under
intensive management system ----------------------------------------- 75
Table 12: Semen parameters of turkeys fed with different protein levels 76
Table 13: Distribution of Experimental Animals to Treatments ---------- 81
Table 14: Nutrient Composition of the Breeder Diet per 100kg ---------- 82
Table 15: Lay out of experiment 1(semen evaluation) --------------------- 83
Table 16: Insemination of Turkey hens based on frequency of
Semen Collection and rearing methods ---------------------------- 87
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Table 17: Polling of semen from groups and pan for insemination
of hens ---------------------------------------------------------------
Table 18: Mean ± SE of semen quality traits of toms ejaculated
at various frequencies under intensive and semi- intensive systems
of management ---------------------------------------------------------- 91
Table 19: Effect of Interaction between Management Systems and
Ejaculation Frequencies on Semen Quality Parameters of Local
Turkeys -------------------------- ----------------------------- -------
Table 20: Mean ± SE of fertility and hatchability of local turkeys under
intensive and semi- intensive systems of management -----------
Table 21: Effect of Interaction between Management Systems and
Ejaculation Frequency on Fertility and Hatchability Parameters
of Local Turkeys ------------------------------------------------------
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105
113
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x
ABSTRACT
Two experiments were conducted to determine the effect of frequency of semen collection
and management systems on semen quality, fertility and hatchability of local turkeys in
the humid tropics. A total of 72 local Nigerian turkeys comprising 24 males and 48
females were used for the study at 36 weeks of age with average body weight of 9kg for
the males and 4kg for the females. The males were randomly divided into two groups (1
and 2) with 12 males in each group. Group 1 males were intensively managed and fed
17% crude protein and 12.6 MJ/kg metabolizable energy breeder diet. Group 2 males
were semi-intensively managed and subjected to free-range condition and given
supplements. The males in both groups were subjected to four frequencies of semen
collection (once, twice, three times and four times) weekly using abdominal massage
technique. A total number of 286 ejaculates were collected and analyzed for volume,
motility, sperm concentration, live sperm, normal sperm, abnormal sperm and total sperm
in ejaculate. The forty eight hens were randomly divided into two groups (1 and 2)
corresponding to the male groups, with 24 hens in both groups, 6 hens per each
ejaculation frequency. The hens were sexually stimulated by ‘venting’ and inseminated
with 0.25ml of semen weekly during late afternoon. A total number of 729 eggs were
incubated and analyzed for fertility and hatchability. The results showed that ejaculation
frequency had significant (P < 0.05) effect on all the semen quality parameters measured.
Two times per week semen collection yielded the highest ejaculate volume, sperm motility
and normal sperm in both management groups compared to other ejaculation frequencies
in both intensive and semi-intensive management systems respectively. The semi-
intensively managed toms had higher (P<0.05) mean values for motility, and live sperm.
Sperm concentration values were similar among intensively and semi-intensively
managed toms at all ejaculation frequencies. Abnormal sperm values were significantly
(P< 0.05) highest in both groups under once per week ejaculation frequency and lowest
in toms ejaculated twice per week. Increasing frequency of semen collection above twice
per week decreased semen volume, sperm concentration and total sperm in ejaculate.
Increasing frequency of semen collection increased progressive motility percentage live
sperm and abnormal sperm. There was no significant interaction (P > 0.05) effect
between management system and ejaculation frequency on all semen quality, parameters
measured. Fertility and hatchability results indicated significant (P <0.05) effect of
ejaculation frequency on all parameters measured. Percentage fertility ranged from
71.01 ± 2.65% to 92.18 ± 21.18. Out of a total number of 729 eggs incubated, 614 eggs
were fertile. Percentage hatchability results obtained in this study ranged from 85.11 ±
4.20% to 100.00 ±0.00% in both management systems. There was no significant
interaction (P > 0.05) between management systems and frequency of semen collection
on fertility and hatchability of local turkey eggs. It was concluded that two times per
week collection frequency was ideal for local toms used for AI programmes while toms to
be used can perform well in the programme under both management systems.
CHAPTER ONE
1.0 INTRODUCTION
1.1 Background of the Study
Food insecurity which is felt in most developing nations including
Nigeria over the years has accentuated the already critical animal protein
deficiency among human populations. High cost of livestock and poultry has
limited the capacity of an average Nigerian to consume adequate quantity and
quality of animal protein (Hamzat et al., 2003). Emeruwah (1999), and
Ojewola, et al. (2004) prescribed massive production of animals with short
reproduction cycles such as pigs, rabbits and poultry as the only remedy to the
acute animal protein shortage in Nigeria. This however, has undoubtedly
spurred research efforts in the direction of these animals that offer the highest
turn-over rate and the quickest return on investment. Obviously, rabbit meat is
not popular in Nigeria and its commercialization is limited by unknown factors.
Pigs on the other hand suffer religious alienation. Thus, poultry has been the
animal of choice (Sanni and Ogundipe, 2003). Although, production of local
chicken is evident, large scale, medium scale and the back-yard poultry
production enterprises are gaining ground in Nigeria as producers now mostly
rear more productive exotic broiler and layer types of chicken which have
shown considerable levels of adaptation to the prevailing environmental
conditions.
Okpeku, et al. (2003) noted that the exotic chickens require expensive
inputs as a result of which, it is becoming increasingly difficult to sustain the
poultry industry over the years under a poor economy .The prevalent high
1
2
exchange rate of the naira to foreign currency needed for importation of parent
stock and some feed ingredients not found locally is not helping matters.
Onyimonyi and Onukwufor (2003) opined that the ban on importation of
poultry meat and egg by Nigerian government may bring to an end the era of
egg glut and low market for locally produced poultry meat and above all,
encourage local production of chicken. Although, their assumptions appear to
be the case, poultry meat and egg are apparently becoming ostentatious. The
Smallholder Family Poultry Concept for Food Security and Poverty Alleviation
in Nigeria has no doubt shown how other local poultry resources can improve
rural livelihood (Sonaiya, 2002b). Therefore, the emphasis on the need to
consider other poultry resources while combating animal protein shortage in
Nigeria has formed the backbone of this study.
Turkey farming is very popular in the Western countries. The major
producing countries are the United States of America, Germany, France, Italy,
Netherlands and the United Kingdom. In 2004, the estimated world turkey
meat production was 4.94 million tonnes (Central Poultry Development
Organization, 2008). However, Nigeria‟s contribution to the above statistic is
not known. Commercial breeds and strains of turkeys such as Broad Breasted
Bronze, Broad Breasted White, White Nicholas 300, Big-6, Hybrid Large
White and a host of others have been developed by University Research
Stations and reputable commercial turkey breeding companies in the Western
world. Strong preference and elaborate research reports have been focused on
these modern turkeys as a result of which they have been highly bred for
3
intensive production. There are however, other types that thrive as scavengers
under the extensive system of production practiced in localities of developing
countries. They roam about, feeding on fresh grasses, insects, worms and
snails. These genetically undeveloped, self-reliant, heat tolerant and rugged
types are the least studied of all turkeys. Little effort has so far been directed at
improving their productivity under free-range condition (Abeke and Ubani,
2008). Research reports on them are therefore scanty or non-existent
(Zahraddeen, et al., 2005).
Commercial turkey production in Nigeria is still rudimentary. The
reason for this apparent low production seems to be due to lack of appreciation
of its potential role in meat production and national economy or perhaps lack of
understanding and knowledge of its management and production requirements
(Abeke and Ubani, 2008). In Nigeria, turkey is a premium bird. Both local and
exotic breeds are highly valued. Although some level of commercial
production is evident, small stock-holder producers dominate the turkey
industry. Commercial producers develop their flock structures with prolific
exotic “broiler” strain. Back-yard and medium scale farmers operate with local
types and exotic broiler strains in small flock units.
One of the major challenges facing turkey production in Nigeria and
other developing countries is the low capability of the species to reproduce by
natural mating. Breeders who rely on natural mating procedures often
encounter poor results due to the clumsy nature of the toms as a reproductive
partner. Modern turkey hens throughout the world are bred by artificial
4
insemination. This is not because of the genetic merit to be gained, but
primarily because the size and conformation of the male in terms of the
extensive development of pectoral muscles arrived at during genetic selection
for weight gain, culminated in diminished libido and reduced ability to perform
during natural mating (Sexton, 1982; Burke, 1984). Burke (1984) further
observed that modern toms lack the coordination and dexterity to accomplish
sufficient mating to assure high fertility. Partial completion of the mating act
even without transfer of semen to the female results in variable periods of
sexual refractoriness during which time hens normally will not re -mate. The
development of artificial insemination technology over the past decades has
resulted in some significant advances in poultry breeding. The objective of
artificial insemination programme is however not just to produce fertile eggs
but to produce viable poults (Bakst, 1993). The US turkey industry relies on
artificial insemination for the production of 300 million turkeys annually.
Therefore, breeder fertility has been implicated to be of utmost importance to
the overall success of the turkey industry. This is based on the realization that
even the best incubators and hatchery management procedures cannot produce
chicks from infertile eggs (Keith, 2008). In Nigeria, breeder flock produces
high percentage of infertile eggs even with the recommended mating ratio of
1:16 adopted by farmer.
This study has therefore been designed to determine the effects of
ejaculation frequency and management conditions on semen quality, fertility
and hatchability of local turkey eggs in a humid tropical environment.
5
1.2 Statement of the Problem
(i) Amidst fertility problems experienced in turkey production, artificial
insemination has not been reported to be in use in turkey reproduction in
Nigeria. Turkey production is a specialized enterprise and lack of sound
research information on their reproductive requirements has led to the apparent
little flock size and poor output of turkey meat in the country.
(ii) The practice of selecting breeder toms based on appealing phenotypic
characteristics without recourse to their inherent breeding value appears to be
responsible for the apparent small poult hatch at the end of the laying cycle.
This has however continued to wreak monumental economic havoc in both
small and large scale turkey farms in Nigeria.
(iii) Characterization of the local turkey semen for the two major systems of
production adopted by farmers in the humid tropics of Nigeria has not been
done. This has led to the lack of information on the fertilizing ability of these
turkeys for on-farm artificial insemination programmes. Research into the
techniques of assessing the reproductive capacity of breeder toms through
semen quality indices evaluation and the application of artificial insemination
has become imperative in order to break the jinx of infertility in our local
turkey breeder flock.
1.3 Objectives of the Study
This study seeks to:
1. determine the effects of ejaculation frequency on the basic physical
characteristics of local tom semen.
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2. evaluate and compare the semen quality indices of local toms under two
management systems (intensive and semi-intensive systems).
3. determine the fertility of semen and hatchability of local turkey eggs
through artificial insemination as affected by ejaculation frequency and
management systems.
4. to determine the best ejaculation frequency and management system for
optimum fertility of local turkeys.
1.4 Justification of the Study
Turkeys occupy an important position next to chicken in augmenting the
economic and nutritional status in various human populations. Turkey meat has
both nutritional and sensorial properties which make it ideal raw material for
rational and curative nutrition. People prefer turkey meat because of its lean
nature. The protein, fat and energy values of turkey meat are 24%, 6.6% and
162 calories per gram of meat respectively. Minerals like potassium, calcium,
magnesium, iron, selenium, zinc and sodium are present. It is also rich in
essential amino acids and vitamins like niacin, vitamin B6 and B12. It is rich in
unsaturated fatty acids and essential fatty acids and low in cholesterol (Central
Poultry Development Organization, 2008). The future of the Nigerian turkey
industry is bright. Despite the high cost of turkey meat, consumers have
continued to pay high prices for both imported and local turkey meat (Abeke
and Ubani, 2008). This is no doubt, a clear indication of the wide potential
roles of turkey as source of meat and income to the producers. However, due to
the growing interest in turkey production in recent times, turkeys are making
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considerable in-road into the peri-urban and urban markets in Nigeria. The
introduction of the Broad-Breasted strains of turkeys from the western world is
already creating viable grounds for the production of hybrid turkeys with
improved productivity. Improved housing, nutrition, management and
advancement in medical care have resulted in the adoption of intensive
management system in addition to the free range and semi-intensive
management systems of production in many localities. These have led to
marked increase in feed utilization, faster growth and control of several
diseases. The application of artificial insemination on a wide scale to the
Nigerian Turkey industry will boost interest in the production of turkeys which
will further bridge the gap in animal protein supply in the country.
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CHAPTER TWO
LITERATURE REVIEW
2.1 The Reproductive System of the Tom
The primary sex organs of the avian males are the internally placed
paired testes. In domestic birds the testes are located just anterior to the
kidneys and are attached to the dorsal body wall (Hatez, 1985). The primary
function of the testes are production of spermatozoa and the male sex hormone
– testosterone (Burke, 1986). Both testes are functional in the males when
sexually mature (Etches, 1996). In poultry, there is bilateral asymmetry of the
testes (Hafez, 1985). The left testis is (0.5 – 3g) larger in size than the right
testis (Etches, 1996). The gross weight of the paired testes is on the average
25g. The sperm produced per gram of testicular parenchyma is approximately
100 X 106
with a daily sperm production of 2.5 X 106 per ml in chicken (Etches
1996).In sexually mature toms, the mean values for the left and right tests have
been reported to be 6.6 + 0.2 and 6.3 + 0.2 grams respectively (Noirault et al.,
2005). It therefore appears that he left testis is 0.3g heavier than the right testes
in sexually mature toms.
The testes are soft and lack the connective tissue commonly found in
mammals. The great mass of testicular tissue is composed of seminiferous
tubules, with relatively few ley dig cells. Due to their intra-abdominal location,
avian testes function at body temperature of about 41to 42oC. The accessory
organs associated with the testes are relatively undeveloped in birds; birds have
no seminal vesicles, bulbourethral glands, or prostate glands (Hafez 1985;
Etches, 1996). Tightly ad posed to each testis is a short structure often termed
9
epiditymis. The epididymal region consists of efferent tubules that carry sperm
from the testis to a single epidymal duct, which is apparent on the epididymal
surface. Leading from each epididymis is a coiled vas or ductus deferens,
which terminates at a small papilla in the cloaca. Just before its termination,
the vas deferens becomes enlarged and serves as a storage site for spermatozoa.
Each vas deferens penetrates a small papilla and ejects the semen through it
into the cloaca. At the time of sexual excitation, several small folds in the
ventral cloaca become engorged with lymphatic fluid and protrude, forming a
traugh like structure to direct the flow of semen. The phalluses of the rooster,
the tom, and many male birds are small and do not function as intromittent
organs. Semen is transferred to the female by touching the rudimentary phallus
to the everted vagina (Burke, 1998). The vasa deferentia and cloacal
ejaculatory apparatus probably receive both sympathetic and parasympathetic
innervations. External stroking of the base of the tail causes protrusion of the
genitalia and often forceful expulsion of semen from the tom; the viscous
semen is released after pressure is applied to the terminal storage depots in the
vasa deferentia.
2.2 Spermatogenesis in Toms
Spermatogenesis consists of a complex series of germ cell division and
differentiation events that occur in a co-ordinated manner and that require
controlled programmes of stage – specific gene expression (dekretser, 1993;
Desjardins and Ewing, 1993; Knobil and Neill, 1995). The testes, where
spermatogenesis occurs, are 5 – 8oC cooler than the core body temperature in
10
mammalian systems (Knobil and Neill, 1995). In most cases, this decrease in
temperature is achieved by placement of the testes outside of the body cavity
(Harrison and Weiner, 1948 Knobil and Neill, 1995). As a result,
spermatogenesis in mammals has unique testis – specific and temperature-
dependent regulatory process specific to germ cell gene expression (Bunick et
al., 1990; Sarge, et al., 1995). An increase in the temperature of mammalian
testes (5 – 10oC) causes a decrease in sperm production which may lead to
infertility (Moore, 1951).
Research reports on several different physiological states of the avian
testes, located within the body cavity, in relation to the mechanism of avian
spermatogenesis have been advanced (Christine, et al., 1997).
Kardong (1995) reported that the avian testes are cooled below the core
body temperature by evaporative cooling by air flow in the abdominal surface
of the air sacs. Menuam and Richards (1975) reported no significant difference
between the temperature of the abdominal air sacs and the core body
temperature, suggesting that the testes are most likely not cooled by association
with an air sac. It has also been proposed that the avian testes are situated in a
high temperature environment at core body temperature (Etches, 1996). Some
researchers are of the opinion that the avian testes are maintained at core body
temperature with spermatogenesis occurring at that temperature (Waterman,
1971; Etches, 1996). Others believe that there must be compensatory
mechanisms acting to allow for spermatogenesis to occur to completion in
avian species such as occurrence of spermatogenesis at night when testicular
11
temperature is lower (Welty, 1982) or the occurrence of a temperature –
sensitive maturation step in the cooler male sperm storage vesicles (Wolfson,
1954; Middleton, 1972). However, since mature sperm are produced
throughout the day and since fully active mature sperm can be obtained after
passage through the epididymis, a requirement for exclusively nocturnal
spermatogenesis seems unlikely (Howarth, 1983; Lin, et al., 1990). Early
researchers that documented an apparent higher frequency of spermatogenesis
at night did so by counting the number of metaphase cells in a testis cross-
section at various times of the day (Macartney, 1942).
In a study to determine testicular temperature rhythms and the effects of
constant light on testicular function in domestic fowl, Christine, et al. (1997)
reported that the testes are not cooled by association with an air sac and indeed
are not cooled by any other mechanism. Therefore, spermatogenesis occurs in
the domestic fowl at the core body temperature of 40 – 41oC.
Thus, while most mammals evolved external and cooler testes which
make the testes much more adapted to elevated temperatures, Aves, have
evolved testes that function efficiently at elevated core body temperature. It is
now known that the seminiferous tubules display waves and cycles of
spermatogenesis in the aves. (Bearden et al., 2004; Noirault et al., 2006). Over
all, the various stages of spermatogenesis in avian species appear to be of
shorter duration than the corresponding stages in mammals (Christine et al.,
1997). For example, while the time from the onset of meiosis to the end of
spermatogenesis is about 26 days in mouse, 29.5 days in ram, 37 days in bull,
12
45.5 days in human, it is only 14 days in drake, 11 days in the quail 14 days in
guinea fowl, and 12.8 days in cockerel (Hafez and Hafez, 2000; Noirault et a.,l
2005). Noirault et al. (2005) reported that cellular associations between specific
stages of spermatogenesis and morphology of cells forming the seminiferous
epithelium in turkeys are similar to those reported in fowl.
2.3 Factors that affect Semen Production
There are inherent variations in semen production between different
species of poultry and between individuals within strains and breeds (Lake,
1982). According to Anderson (2001) there are many factors that may
influence the production of semen and a thorough knowledge of the tom‟s
physiology is essential to enable an understanding of male fertility. There are
many factors that may affect the male and may influence semen production.
The reproductive functions in males are endocrine controlled by the pituitary –
hypophyseal-gonadal axis which influences the normal physiological processes
that regulate spermatogenic mechanism. Factors that affect reproductive
efficiency in the toms can be grouped as follows:
Ambient temperature
Nutrition
Age
Frequency of semen collection
Semen collection technique
Photoperiod
Breed/species variation
13
2.3.1 Ambient Temperature
Direct climatic factors acting on the birds include high ambient
temperature and relative humidity, resulting in severe heat stress (Bearden et
al., 2004). Heat stress can be one of the main limitations in poultry production
and reproduction, more especially in hot areas. Elevated environmental
temperatures pose a threat to the general well-being of the males. An increase
in the body temperature without a rapid compensation for heat loss, resulting
from a prolonged exposure to environmental temperature, may cause a change
in the body temperature of the tom, leading to a significant impairment of
semen production and reproduction. The intensity and duration of elevated
environmental temperature combined with relative humidity may also affect
the behavioural, and hormonal patterns of the toms. Such detrimental effects
limit reproductive characteristics of the tom thus, inhibiting spermatogenesis
and a decrease in the secretion of gonadotrophin, Obidi et al., 2008). As body
temperature increases, sperm metabolism, sperm motility and sperm quality
become generally lower. Froman and Feltman (2005) found sperm to be motile
at 410C motility declines soon after ejaculation.
2.3.2 Photoperiod or daylight length
Most domestic birds in temperate climate are seasonal breeders and in
most birds, photoperiod stimulates spermatogenesis. The duration and
intensity of photoperiod may have an effect on the conditioning of the toms for
semen production (Anderson, 2001). Short days do not stimulate gonadotropin
secretion, as they do not illuminate the photosensitive phase. However, long
14
days illuminate the photosensitive phase and therefore gonadotropin secretion.
Photo-schedules in poultry production are currently being practiced, and
designed to maximize the yield of semen for a prolonged period, by delaying
the onset of photo refractoriness. In addition, the generation interval can be
reduced when photo stimulation is practiced at earlier age (Etches, 1960).
Time of the day for the collection of semen also affects the quality and
quantity of semen. Semen production has been noted to be higher when
collected in morning and evening when the environment is cooler (Peters et al.,
2008). The onset of reproduction in avian males occur when light, acting
through photoreceptors in the brain, provides neural signal which the bird‟s
reproductive endocrine system perceive as a change in day light length,
sufficient to initiate reproduction (Hafez and Hafez, 2000).
Noirault et al. (2005), subjected four groups of toms of different ages to
different photoperiods of 10.5L: 13.5D; 14L: 10D; 6L: 2.5D; 6L: 3.5D and
reported their weekly sperm output (WSO) as shown in Table 1 below:
Table 1: Effects of age and photoperiod on weekly sperm output of toms
( x + SE).
Age wk WSO(x109)/Treatment group
Group 1 Group 2 Group 3 Group 4
30-31
32 – 33
39 – 40
45 – 46
51 – 52
57 – 58
7.1 + 0.8
7.1 + 0.8
7.8 + 0.8
9.2 + 0.5
9.4 + 0.7
8.8 + 0.9
8.7 + 0.1 1.6 + 0.7 3.0 + 0.8
7.9 + 0.9 1.6 + 0.7 3.9 + 0.8
8.0 + 0.9 1.7 + 0.7 4.5 + 0.7
8.9 + 0.9 6.0 + 1.2 8.1 + 0.7
10.1 + 1.1 6.0 + 1.3 9.3 + 1.1
8.0 + 0.9 6.0 + 1.3 9.7 + 0.7
Group 1 (20.5L: 13.5D), Group 2 (14L: 10D), Group 3 (6L: 2.5D), group 4
(6L: 3.5D).
15
2.3.3 Nutrition
Lack of proper nutrition can reduce reproductive efficiency. Feed and
water restriction cause stress in birds, induce males to lose body weight,
leading to a permanent non functional testes and a reduced reproductive
performance in mature males (Etches, 1996). Many nutrition-related problems
in reproduction are due to either under feeding or over feeding of energy or
protein. Energy is unique because, in terms of length of reproductive life, over
feeding is more detrimental than underfeeding. Over feeding results in excess
fat deposition with fat infiltrating the liver (fatty liver syndrome) and
sometimes the reproductive organs. Such animals have less resistance to
infectious diseases and other stressors. Over conditioned males are more likely
to have foot and leg problems, with reduced libido (Bearden et al., 2004).
Ejaculate volume, sperm density, and fertilizing ability of toms can be affected
by restricted feed intake (Etches, 1996). Underfeeding of energy will delay
puberty in both males and females delaying onset and rates of spermatogenesis,
ovulation, and libido in males and females respectively (Etches, 1996; Bearden
et al., 2004).
2.3.4 Age
In poultry species, semen quality parameters such as volume,
concentration and motility change negatively with increasing age of the male,
leading to a progressive decline in infertility (Thatohatsi, 2009). In cockerels, it
has been shown that increasing age negatively affects the biochemical
parameters of semen (Hafez and Hafez, 2000). Similarly, Kotlowska et al.
16
(2005) and Tuncer et al. (2006) reported changes in semen quantity and quality
to be related to increasing age in cockerels.
2.3.4 Breed/ Species Variation
Research reports indicate that semen quality traits vary according to
breeds and species (Machebe and Ezekwe, 2000). Nwachukwu et al. (2006)
reported that Naked Neck and Frizzled genotypes produced higher ejaculates
than the Normal feathered breeds of cockerels. Similar, Zahraddeen et al.
(2005) reported higher semen volume and other seminal characteristics for
exotic white Nicholas toms than the local breed of toms.
2.4 Semen Collection Technique
Semen collection is like harvesting any other farm crop. Effective
harvest of semen involves obtaining the maximum number of sperm of highest
possible quality in each ejaculate. This involves proper semen collection
procedures used on males that are sexually stimulated and prepared. The initial
quality of semen is determined by the male and cannot be improved even with
superior handling and processing methods. Semen quality can be lowered, by
improper collection and processing techniques. Semen collection is a complex
procedure involving coordinated efforts between the animal handler and the
collector (Bearden et al., 2004).
2.4.1 Handling Male Turkeys for Collection of Good Quality Semen
There are several ways of handling toms to stimulate ejaculation, the
simplest and most commonly used technique usually requires two people. The
first person (the operator) holds the bird‟s legs and the semen collection
17
tube/aspirator. The second person (the milker) massages the area around the
cloaca. The steps to be taken are as described below.
Place the tom on its chest in a vertical position with its neck under one thigh
of the milker and its legs over the milker‟s other thigh. The legs of the bird
are held firmly in place together with the left hand of the first operator.
Protrusion of the phallus is brought about by massaging the soft part of
abdomen with the fingers and thumb of the left hand. At the same time, the
tail is pushed back over the toms back with the heel of the right hand. The
tom can be further stimulated with the palm passing gently over the vent in
the same sequence. In a series of simultaneous movements, the operator
maintains the pressure on the tail head until the thumb and index finger of
the left hand are in position to squeeze behind the phallus, while the heel of
the left hand maintains the pressure on the tail head.
Using the index finger of the right hand, the second operator applies
pressure below the phallus. It is very important to place the thumb and
index finger well behind the protruded phallus in order to squeeze the
bulbous ductus. The pressure applied will determine the flow of semen.
Care should be taken to apply an aspiration rate that will pick up the semen
slowly. Too high an aspiration rate leads to damage of the tail of the
spermatozoa, which results in poor fertility. To minimize collection of
unwanted contaminants such as urates and fecal materials, the following
steps should be observed:
18
The first operator should not go up the Phallus further into the cloacal
region during aspiration.
The toms should not be fed 4-6 hours prior to semen collection. If semen is
to be collected in the morning, feeding should be delayed until after semen
collection.
Adequate light should be provided in the collection arena to ensure easy
visual inspection of the quality of semen (www.hybridturkeys.com,
accessed 2010).
2.5 Frequency of Semen Collection in Turkeys
Mating behaviour patterns in chickens (Baur and Bakst, 1985) and
turkeys (Carte and Leighton, 1968) have been reported. Among birds, mating
habits vary from monogamous to promiscuity. Studies with chickens revealed
that cockerels may mate up to 30 times in a day but more than 50 percent of the
matings are not associated with release of semen (Burke 1984). Bahr and
Bakst (1985) reported that libido in the male is not necessarily correlated with
high fertility and that there is a tendency for the most frequent copulator to
produce many aspermic ejaculates. Reports on the number of times an average
tom can mate in a day with or without release of semen are apparently lacking.
However, under experimental conditions, toms have been ejaculated at various
frequencies and the quality of the successive ejaculates evaluated. Zahraddeen
et al. (2005) ejaculated both local and exotic toms up to 3 times per week and
reported a progressive decrease in semen volume and sperm concentration with
increasing frequency of ejaculation in both breeds, other seminal characteristic
19
were unaffected. Similarly, Thatohatsi (2010) reported that sperm
concentration appears to be the only seminal traits affected by frequency of
ejaculation, declining progressively with an increase in ejaculation frequency.
The relative advantages and disadvantages of high and low frequencies of
semen collection have been well documented in fowl by McDaniel and Sexton
(1977). In the absence of a definite effect on fertility, and given that fowl hens
are inseminated at weekly intervals, these authors concluded that, by
influencing the number of spermatozoa available per day or per week, the
frequency of semen collection in chicken influences the number of semen
doses available for insemination. In agreement with previous studies, in
turkeys McCartney et al. (1958); Cecil (1982) reported that increasing the
frequency of semen collection had negative effects on ejaculate volume without
significantly affecting sperm concentration and other sperm physical
characteristics. In cockerels, it has been reported that increasing ejaculation
frequency negatively affected biochemical parameters of semen. In boars, it has
also been reported that increasing frequency of semen collection caused
temporary loss of fertility (Hafez and Hafez, 2000; Kotlowska et al., 2005;
Tuncer et al., 2006). Noirault and Brillard, (1999) ejaculated British United
Turkeys seven times per week and reported their daily sperm output as shown
in Table 2
20
Table 2: Daily sperm output of turkeys subjected to various frequencies of semen
collection ( x + SE)
Frequency Daily sperm output (x109)
Once every two weeks
Once per week
Twice per week
Three time per week
Five times per week
Seven times per week
0.32 + 0.05
0.62 + 0.11
1.14 + 0.11
1.53 + 0.12
1.93 + 0.13
2.03 + 0.19
Noirault and Brillard (1999), studied the effects of frequency of semen
collection on the quantitative characteristic of turkey breeder males and
reported that motility is negatively affected following a rest period of 2 days or
more in a 5 times semen collection frequency. The authors also observed a
persistent but moderate, increase in percentage viable spermatozoa from males
collected more frequently.
2.5.1 Factors Affecting post-ejaculation Semen Quality
A number of factors have been identified to affect ejaculate quality in
vitro. These factors included:-
2.5.2 Ambient temperature
A decrease in ambient temperature after collection of semen reduces
sperm motility (Anderson, 2001). High ambient temperatures increase the
metabolic rate of sperm cells (Hafez and Hafez, 2000). Sperm membrane has
been reported to be susceptible to changes in temperature which tend to affect
the movement of sperm, resulting in deterioration in quality and reduced
fertilizing capacity (Senger, 2003). In addition, semen for use in artificial
insemination should not be exposed to sun light (Anderson, 2001).
21
2.5.3 Semen Osmotic Pressure
Latif et al (2005) reported that an increase in osmotic pressure of semen
can be ascribed to contamination with uriate and bacteria, resulting in the
clumping of sperm. An osmotic pressure of 330m which is identical to that of
seminal plasma is optimum for short term storage of turkey semen (Thurston
1995). Hypo-osmotic conditions result in swelling of the sperm head
(Lukaszewicz et al., 2008). The semen diluents must be isotonic, as adverse
osmotic pressure created by some diluents may be detrimental to viability and
fertility of sperm cells (Senger, 2003).
2.5.4 Semen pH
The pH of semen is slightly acidic (pH 6.8) or below neutral (pH 7.0)
immediately after ejaculation in most poultry species. The loss in CO2 may
result in an increase of pH, which may again be neutralized by the production
of lactic acid during sperm metabolism (Cole and Cupps., 1977).
2.5.5 Concentration of sperm in ejaculate
The sperm cell contains Potassium (K+) as a major cation, and Sodium
(Na++
) as the principal cation in the seminal plasma. Potassium is a natural
metabolic inhibitor and by increasing the cellular concentration, it increases the
ratio of potassium to sodium which reduces the metabolic activity of sperm. In
vitro, addition of fructose will not greatly change the metabolic rate, but will
extend the life span of the sperm. Excessive dilutions suppress sperm motility
and the metabolic rate of the sperm (Nishiyama, 1961; Beardem et al., 2004;
Thatohatsi, 2010).
22
2.5.6 Gases
A low concentration of CO2 stimulates aerobic metabolism of sperm
(Thatohatsi, 2009). The metabolic rate is suppressed if the partial pressure
exceeds 5%. Oxygen is necessary for aerobic metabolism, but higher levels of
oxygen may be toxic, and depress the metabolic rate. This factor is not likely to
occur in the laboratory unless the O2 or CO2 is bubbled through the semen
(Bearden et al., 2004), it has been demonstrated that light causes a photo-
chemical reaction in semen that result in the production of hydrogen peroxide,
which is detrimental to the sperm (Anderson, 2007).
2.5.8 Bacterial Contaminants
There are a variety of bacteria that could contaminate the semen after
collection (Hafez, 1988). This can be minimized by cleaning the cloacal area
before collection and by using sterile equipment during collection. Some non-
pathogenic organisms compete with semen for nutrients and produce
metabolites that may have adverse effect on sperm viability. The use of
antibacterial agents such as Gentamicin, Tylosin and Linco-spectin during
processing and storage will limit bacterial growth, thus saving energy
substrates for sperm metabolism and maintenance (Etches, 1996; Bearden et a
l., 2004).
2.6 Semen Quality Evaluation
Once semen is collected, it is evaluated for quality (Donoghue, 1998)
Methods of assessing the quality of ejaculate from domestic fowl and other
animals, and the estimation of their value as predictors of sperm fertilizing
23
ability have been established for many decades (Wilson, et al; 1979; Cooper
and Rowell, 1958). Evaluation of semen quality is of great economic
importance from the point of view of artificial insemination (Siudzinska and
Lukaszewicz, 2008). This is because, the male plays a dominant role in fertility
rather than the female (Etches, 1996) Thus, most fertility problems have been
blamed on the male (Munro, 1964; Etches, 1996). This is so because most
females normally contribute their ova in appreciable number based on their
innate laying ability (Omeje and Ude, 1998). At present stage of technology in
animal reproduction, the greatest selection pressure is exerted against the
male‟s gamete. The male is immensely more capable of yielding a harvest of
germinal cells than the female, and spermatozoa from a single sire are used to
fertilize oocytes in as many dams as possible. From this point of view, sub-
maximal fertility in individual males is of greater consequence than sub-
maximal fertility in individual females (McDonald, 2003). Just like in` males
of many domestic animals, the fertilizing potential of turkey breeder toms
varies, even within a flock. Thus, some males are extremely fertile and produce
maximum number of high quality sperm; while others are sub-fertile and do not
produce enough good sperm (McDonald, 2004). The amount of work invested
in understanding the link between the tom and fertility is easily justified when
evaluating the impact poor semen quality has on turkey production (Judd,
2001).
In livestock production systems in which artificial insemination (AI) is
practiced, semen analysis is fundamental to sire selection and reproductive
24
management with the goal of identifying and culling males that are unlikely to
produce progeny (Kemmerer et al., 1971; Donoghue, 1998, Donoghue, 2005).
If fertility is to be managed and optimized from the male perspective,
assessment of sperm quality and culling of poor males need to be incorporated
into management procedures (Donoghue, 1998). During the breeding season,
the utilization of breeder toms with predetermined high fertilizing potential has
been found to result in improved reproductive efficiency (Kammerer et al.,
1971). There are many parameters that can be used to evaluate the quality of
turkey semen and estimate the fertilizing potential of the donor males. These
parameters are:
1. Semen colour
2. Semen volume
3. Progressive motility
4. Sperm concentration
5. Normal and abnormal sperm
6. Live and dead sperm
7. Biochemical parameters
2.6.1 Semen Colour
Gross appearance of ejaculated semen is used to evaluate semen for
quality (Bearden et al., 2004). Good quality turkey semen should be viscous
and cream-white (Bearden et al, 2004: Hafez, 1985). Samples with low
concentration will appear watery or less opaque. Pink tinge appearance is an
indication of blood contamination. Yellow samples usually have offensive
25
odour. The use of semen that is discoloured, watery, or contaminated by fecal
material, urates, or blood will lead to lowered fertility particularly if the semen
is subjected to short-term or long-term storage. All contaminated samples
should be discarded (Hafez, 1985; Bearden et al., 2004).
2.6.2 Semen Volume
The volume of ejaculated semen is determined not only for use in
processing but also to establish a pattern for individual male. Deviations from
this pattern particularly downwards indicate a problem. The problem may be
due to health factors or it could be an indication that the semen collection
procedure for the particular male needs reversion (Bearden et al, 2004).
Ejaculates with larger volume, higher concentration, and higher motility will
have higher fertility in most cases and more breeding units can be prepared
from an ejaculate, thus, reducing the processing time and cost per breeding
unit. In addition, the lifetime output of sperm by an individual male is
increased. In a fertility study where hens were artificially inseminated with
0.025ml of semen bi- weekly Nestor and Brown (1976) reported a positive
correlation between semen volume and fertility. Nestor and Renner (1968)
suggested that toms could be selected for semen volume midway through the
breeding season based on the significant correlation between semen volume
and fertility. Generally, the chicken and turkey ejaculates average about 0.25ml
in volume and about 5 billion sperm per ml and 9 billion sperm per ml
respectively (Hafez, 1985). Genetic improvement with such important
parameters as semen volume and sperm concentration in mind appears to be
26
feasible with the turkey but less likely with the chicken (Sexton, 1983).
Zaharaddeen et al. (2005) subjected White Nicholas toms and local breed of
turkeys to three frequencies of semen collection weekly and recorded the
results of semen volume as shown in Table 3 below:
Table 3: Semen volume of toms subjected to three frequencies of semen
collection.
Similarly, Noirault and Brillard (1999), subjected the British United
Turkeys to seven frequencies of semen collection per week and the mean
values for semen volume for the whole experimental period are shown in Table
4.
Table 4: Semen volume of toms subjected to seven frequencies of semen
collections
Frequency of semen collection Semen volume (ml)
Once every two weeks 0.44 + 0.12
Once per week 0.43 +0.12
Twice per week 0.42 + 0.10
Three times per week 0.37 + 0.09
Five times per week 0.27 + 0.08
Seven times per week 0.25 + 0.02
Many factors influence semen production by male breeders. There are
wide differences in the outset of semen production and in semen quality
Collection
frequency
Semen volume (ml) Semen volume (ml)
White Nicholas Local breed
Once per week 0.28 ± 0.03 0.11 ± 0.34
Twice per week 0.35 ± 0.03 0.12 ± 0.02
Three times per
week
0.31 ± 0.02 0.22 ± 0.03
27
between species, strains within species, and individuals within species. The
factors that affect semen volume in turkey breeder males have been reported to
be breed differences, nutrition, season, disease, technique of semen collection
(Machabe and Ezekwe, 2002).
2.6.3 Motility
Spermatozoa are highly specialized cells that are designed to accomplish
a single objective: fertilization of an ovum. In order to achieve fertilization, the
sperm must first gain access to the egg. The capacity of progressive motility
develops as the morphology and metabolic machinery of the spermatozoa
mature (Hafez, 1983).
Motility of a sample of semen is expressed as the percentage of cells that
are motile under their own power (Bearden et al., 2004). A progressively
motile sperm is one that is moving or progressing from one point to another in
a more or less straight line. Most ejaculates will show other types of motility.
These include both circular and reverse movements due to tail abnormality, and
vibrating or rocking movement often associated with aging (Hafez, 1985;
Bearden et al., 2004). Progressive motility is however, the most important
individual quality test because fertility is highly correlated with the number of
motile sperm inseminated. The percentage motility of an ejaculate of semen
can ranges from 0% to 100% (Gamal and Kanar, 1951; Bearden et al., 2004)
Fertility levels of ejaculates with initial motilities of 50% to 80% are high if the
desired number of motile sperm is present at the time of insemination. Samples
with less than 40% initial motility are not suitable for use unless the ejaculate is
28
from an exceptionally superior sire (Bearden et al., 2004). However, although
motility is essential for fertility as well as an essential feature of good quality
spermatozoa, it is not necessarily an indicative of fertilizing capacity. This is
because spermatozoa tend to lose fertilizing ability before they lose motility.
Furthermore, abnormal spermatozoa may exhibit normal movement and yet be
incapable of fertilizing an egg. This is because during their transport in the
male and female reproductive tracts, spermatozoa encounter different
environments in which they may survive or die. Thus, while motility may assist
in the transport of spermatozoa from the site of deposition to the site of
fertilization, it is probably secondary to other transport mechanisms such as
muscular contractility and ciliary motion of the female reproductive tract.
Sperm motility per se may not be sufficient in facilitating passage through the
female reproductive tract and making possible the actual penetration of the
investments of the ovum (Hafez, 1985). However, semen quality is
traditionally considered in terms of the percentages of progressively motile
sperm or morphologically normal sperm. These have been reported to be
positively correlated with fertilizing ability. The fertilizing ability of turkey
spermatozoa has been reported to be positively correlated with sperm motility
measured by subjective „scoring‟ system. (Cooper and Rowell, 1958., Wilson
et al., 1978; Amann and Katz, 1994 Donoghue, 1998; Bearden et al., 2004) and
by objective light scattering techniques (Bilgilli et al., 1985; Wishart and
Palmer, 1986; Chaudhuri and Wishart, 1988, and Barbato et al., 1997).
Computerized image analysis system are now available for determining both
29
percentage of motile sperm and the distribution profile for velocity and other
kinematic attributes of individual sperm cell (Amann and Katz, 1994). Brown
and Gram (1971) observed that hens inseminated with low number of motile
sperm produced significantly fewer eggs, compared to hens inseminated with
highly motile sperm. Similarly, Kammerer et al. (1972) found a positive
correlation between percentage motile sperm in ejaculate and fertility to be
consistent, and that percentage motile sperm in ejaculate could be used in
predicting fertility.
Recently, a simple sperm mobility assay, based on the ability of
spermatozoa to penetrate, and thus increase the turbidity of a viscous polymer
solution (Accudenz) has been applied to test turkey sperm quality (Forman and
Mclean, 1996). Sperm mobility has been found to be composed of several
parameters of which sperm motility is a component (Donoghue et al.,
1999).On the basis of sperm mobility assay, semen from males were divided
into high and average mobility groups, which differed by 10% in the proportion
of fertilized eggs laid by inseminated hens (Forman et al, 1997). This test has
additionally shown that sperm quality in individual tom is a trait, which is
repeatable between successive ejaculates in the short and long term and can be
linked to fertilizing ability (Wishart and Palmer, 1986; Chaudhuri et al., 1988;
Froman et al., 1997; 1998).However, a limitation of this objective test of sperm
quality is that it requires special laboratory facilities and lacks the flexibility
required for “on the farm” evaluation (Donoghue, 1999). Although the INT–
tetrazolium dye test introduced by Chaudhuri and Wishart (1988) is relatively
30
robust, and its outcome easily interpreted within a short incubation period,
results obtained so far show strong correlation with other tests of sperm
quality, including fertilizing ability, but the reagents involved in the test are
unstable while some are highly toxic (Chaudhuri et al., 1988).Thus, despite the
problems of bias associated with subjective evaluation, visual assessment of
sperm motility is still the standard method used by most clinical andrology
laboratory (Amann and Katz, 1995).Motility ratings for tom semen as
described by Gamal and Kamar (1959) are as shown in Table 5 below:
31
Table 5: Description of motility grades in farm animals/based on scoring method
Grade motility Rating
O No motility discernible.
1. 10% of the spermatozoa exhibiting slight undulating
movement. Mostly weak and oscillatory.
2. 20% of the spermatozoa exhibiting slight movement.
Few active spermatozoa.
3. 30% of the spermatozoa showing undulatory
movement. No waves or eddies formed.
4. 40% of the spermatozoa showing undulatory
movement. Large number of inactive spermatozoa.
5. 50% of the spermatozoa showing progressive motility.
Slowly moving waves and eddies produce.
6. 60% of the spermatozoa showing progressive motility.
Vigorous motion. A few inactive spermatozoa.
7. 70% of the spermatozoa showing progressive motility.
Less inactive spermatozoa.
8. 80% of the spermatozoa showing progressive motility.
Waves and eddies of great rapidity of movement.
9. 90% of the spermatozoa in vigorous and progressive
movement.
10. 100% of the spermatozoa in vigorous and progressive
movement. Extremely rapid formation of eddies and
movement.
Zaharaddeen et al. (2005) subjected White Nicholas toms and local
breed of turkey toms to various frequencies of semen collection and reported
their mean motility values as shown in Table 6 below:
32
Table 6: Sperm motility (%) of toms subjected to various frequencies of
semen collection
Collection Frequency Percentage sperm
motility
Percentage sperm
motility
White Nicholas Local breed
Once 82.11 + 3.04 84.25 + 2.23
Twice 83.47 + 2.34 83.47 + 2.36
Three times 81.92 + 2.64 80.17+ 2.64
Noiraut and Brillard (1999) subjected the British United Turkey toms to
different frequencies of semen collection and reported their mean motility
values as shown in Table 7 below:
Table 7: Mean percentage sperm motility of toms subjected to various
frequencies of semen collection
Frequency Sperm motility (%)
Once every two weeks 85.11 + 0.54
Once per week 86.88 + 0.63
Twice per week 87.41 + 0.40
Three times per week 88.15 + 0.26
Five times per week 89.69 + 0.33
Factors That Affect Sperm Motility
Several endogenous and exogenous factors affect sperm motility (Hafez,
1985). Selenium may be involved in the maintenance of structural integrity and
locomotor function of spermatozoa (Segerson et al., 1981). Various microbial
contaminants such as ureaplasma may adversely affect sperm motility and
morphology (Hafez, 1985). A variety of structural defects of spermatozoa due
33
to disease, high environmental temperature, cold shock, freezing and thawing,
high-pressure aspiration, prolonged in vitro storage, tend to affect sperm
motility (Hafez, 1985).
2.6.4 Sperm Concentration
Sperm cell concentration is defined as the number of sperm cells per ml
of ejaculate (Bearden et al., 2004). Accurate determination of the number of
spermatozoa per milliliter of semen is extremely important because it is a
variable semen quantity parameter. When combined with the volume of the
ejaculate, sperm concentration not only provides a basis for calculating the
number of sperm per insemination dose, but also serves as a measure of semen
quality (Hafez, 1985; Bearden et al., 2004). Tom-to-tom differences and
differences between semen collectors will affect sperm concentration. One
however derives several advantages by determining sperm concentration.
Knowledge of sperm concentration not only provides a basis for calculating the
number of sperm per insemination dose but also serves as a measure of semen
quality (Bearden et al., 2004; Christensen, 1981). Kammerer et al. (1972)
found a positive correlation between sperm concentration and fertility. In
addition, a significant (P<0.05) relationship between sperm concentration and
fertility was found to exist. Kammerer et al. (1972) and Brown et al. (1970)
also found a positive correlation between sperm concentration and fertility rate
in the reproductive period. Zaharaddeen et al. (2005), ejaculated White
Nicholas toms and local breed of turkey three times weekly under intensive
34
management system and recorded the mean values for sperm concentration as
shown in Table 8 below:
Table 8: Sperm concentration of toms subjected to three frequencies of
semen collection.
Frequency Sperm concentration (x
109)
Sperm Concentration
(x 109)
Exotic breed Local breed
Once per week
Twice per week
Three times per week
8.04 + 48.50
3.87 + 117.40
2.07 + 95.86
2.80 + 166.03
2.87 + 117.40
2.75 + 97.86
Similarly, Noirault and Brillard (1999), ejaculated British United Turkey toms
at different frequencies per week and recorded the mean values for sperm
concentration as shown in Table 9 below
Table 9: Sperm concentration of toms subjected at various frequencies of
semen collection ( x + S E)
Frequency Concentration (x 109)
Once every two weeks
Once per week
Twice per week
Three times per week
Five times per week
Seven times per week
11.07 + 0.15
10.94 + 0.35
10.71 + 0.24
10.71 + 0.27
10.04 + 0.36
9.82 + 0.51
Bearden et al. (2004) reported that ejaculates containing less than 500
million cells per ml have been associated with low fertility rate. Kammerer
(1972), found a positive correlation between sperm concentration and fertility.
In a fertility study where hens were artificially inseminated with 0.025ml
(containing 2 billion sperm cells) of semen bi-weekly, Nestor and Brown
35
(1976) reported a positive correlation between sperm concentration and
fertility. In an in vitro study, Bramwel et al. (1995) inseminated exotic turkey
hens with semen containing 100, 50 and 25 million sperm cells and recorded
the mean sperm penetration holes of 40.2, 19.5 and 14.1; on the perivitelline
membrane of the ova; for 100, 50 and 25 million sperm cells respectively.
Generally, chicken and turkey ejaculates average about 0.25 ml in volume and
about 5 billion sperm per ml and 9 billion sperm per ml respectively (Hafez,
1985). Lower sperm concentration could be indicative of a problem. The
problem may be due to disease or insufficient stimulation of the male prior to
collection (Hafez, 1985, Bearden et al., 2004). Although research reports on
semen quality, fertility and hatchability of turkeys under intensive management
system abound, there is paucity of information on semen quality indices of
turkeys under range and semi-intensive management systems.
2.6.5 Normal and Abnormal Sperm
The normal spermatozoon is composed of a head and a tail that is
divided into a mid piece, main-piece, and end-piece. Every ejaculate of semen
will contain some morphologically abnormal spermatozoa. The expected range
of 8% to 10% has no adverse effect on fertility. If the accumulated total
abnormal spermatozoa exceed 25% of the total ejaculate, reduced fertility may
be anticipated (Bearden et al., 2004). Morphological abnormality of sperm can
be classified under abnormal heads (primary abnormalities), cytoplasmic
droplets (secondary abnormalities) and abnormal tails (tertiary abnormalities)
Environmental stressors and high frequency of ejaculation have been
36
implicated to increase the number of abnormal spermatozoa in an ejaculate
(Hafez, 1985; Bearden et al., 2004). Among all types of morphological
abnormalities, the first to appear, and the last to disappear are the cytoplasmic
droplets. Cytoplasmic droplet on the tail of ejaculated sperm is an indication
that the maturation process is not completed (Bearden et al., 2004). Sampson
and Warren (1939), Raimo (1943), and Bearden et al, (2004), found a
significant negative correlation between percentage abnormal sperm and
fertility. Similarly, Allen and Champion (1955) found a negative correlation
between percentage abnormal spermatozoa and percentage hatchability of eggs.
2.6.6 Live and Dead Sperm
The proportion of live and dead cells can be estimated by supravital
staining with a stain mixture such as nigrosin-eosin. The cells that were alive
when the stain was applied exclude the stain, and the dead cells stain red with
eosin against the dark nigrosin background. The results live sperm counts are
highly correlated with visual estimates of progressively motile sperm cells, but
the later averages are lower than the percentage of unstained spermatozoa
(Hafez, 1985; Bearden et al., 2004).
2.7 Biochemical Parameters
Such parameters as protein and cholesterol concentration and activities
of acid phosphatase (AcP), asparatate aminotransaminase, amidase, and
antiproteinase (AaP), have been described for turkey seminal plasma (Hess and
Thurston, 1984; Thurston et al., 1993; Kotlowska et al., 2005). The levels of
these biochemical parameters are linked to semen quality and to the occurrence
37
of yellow semen syndrome (Thurston et al., 1982; Hess and Thurston, 1984;
Thurston and Korn, 1997; Kotlowska et al., 2005).Biochemical parameters
have been linked to various functions of male reproductive tract. Acid
phosphatase activity of turkey semen can be released from damaged
spermatozoa (Graham et al., 1070) or delivered from ductal epithelia (Bell and
Lake, 1962; Lake, 1962). In mammals, an increased level of this parameter is
used as a marker enzyme for functional analysis of reproductive system
(Aumuller, 1989; Nguyen et al., 1990). The epithelial cells of the deferent
ducts are also the main source of proteolytic and antiproteinase activity of
turkey semen (Holsberger et al., 2002; Kotlowska et al., 2005). The potential
role of proteinase inhibitors is to protect the sperm duct epithelial cells, seminal
plasma proteins, or viable spermatozoa from the potential detrimental
proteolytic action of acrosin liberated from the acrosomes of dead and damaged
spermatozoa and serine proteinases present in the seminal plasma of turkeys
(Thurston et al., 1993; Kotlowska et al., 2005).
However, no single measurement of seminal quality has been found to
be a reliable criterion for predicting fertility of a given male (McDonald, 2003).
Success in a diagnostic test is not measured by correlations between values for
the trait measured and actual eggs yielding a chick or poult. Correlations hide
substantial error (Donoghue, 1998). As noted by Hammerstedt (1996),
concepts familiar to those establishing endocrine or clinical assays, namely
precision, specificity and sensitivity can be used to establish the correctness of
predictions. Results from many sperm quality assays do not predict fertility
38
(Wishart, 1995), and those that do usually are time consuming or technically
difficult (Donoghue, 1998). Most methods appropriate for predicting fertility
have not been adapted to large scale application (Donoghue, 1999). In
commercial farms, sperm quality test must be compatible with the existing
breeder management procedure (Donoghue 1998). Further, many of those tests
evaluate a single characteristic of sperm (Amann and Hammerstedt, 1993) and
do not account for the complex process of fertility, which involves sperm
transport and storage in the female tract and sperm binding and penetration of
ovum (Bakst et al., 1994; Robertson et al, 1998). Thus, artificial insemination
should be incorporated as part of in-vitro sperm quality evaluation for better
precision of the fertilizing potential of high quality ejaculates.
2.8 Basic Anatomy and Physiology of the Hen’s Reproductive Tract
The reproductive tract of the hen is suspended in the body cavity by a
ligament that attaches the tract throughout its entire length to the dorsolateral
part of the body cavity. In most hens, only a left oviduct is present. The oviduct
comprises the infundibulum which is the site of fertilization and engulfs the
ovulated ovum. The narrower part of the infundibulum is known as the
chalaziferous region, and contributes in the formation of the chalazae and is
one of the two known sperm storage sites in the oviduct (Hafez and Hafez,
2000). The magnum region is the longest part of the oviduct and is creamy –
white in colour, with thick walls. The majority of protein albumen is formed in
the oviductal tissues of the magnum, and is deposited in the ovum when it
reaches this region (Taylor, 2003). The albumen further constitutes up to 45%
39
of the egg white and is secreted by the tubular glands, found in the magnum
(Etches, 1996). The isthmus region of the oviduct is separated from the
magnum by a narrow translucent area which does not possess any tubular
glands and contributes to the formation of the egg membranes. The
mucosa of the isthmus is folded into primary and secondary ridges which are
aligned longitudinally and the tubular glands in this region have secretory cells
which are believed to secrete the core of the fibres that make up the shell
membrane, while the secretory cells of the epithelium secrete the mantle that
surrounds them (Etches, 1996). About 80% of the time required for egg
formation in the oviduct is spent in the uterus, or shell gland region. The egg
spends 18 – 22 hours in the shell gland of the oviduct, absorbs approximately
15g water, and exchanges several electrolytes, including sodium, potassium
and chlorine. This gland contains several types of secretary cells in both the
epithelium and the tubular gland. Water containing electrolytes is absorbed by
the egg in this region and it decreases with an increase in the rate of
calcification (Taylor , 2003).
40
Fig 1
41
2.8.1 Sperm Storage in vivo
Avian sperm can survive in the female reproductive tract and are
capable of fertilizing eggs for days or weeks in many species. The occurrence
of anatomical structures associated with sperm storage was discovered by Van
Dremmelen (Hatch, 1983). The genital tract of the hen has crypts called sperm
nests, sperm glands or sperm host gland which occur in the infundibulum and
the uterovaginal junction. Sperm introduced by natural mating or artificial
insemination are stored in these crypts and retain their fertilizing ability for a
long period of time (Koyanagi and nishiyama, 1981) for about two weeks in
turkeys (Hafez 1985). A model accounting for the mechanism of sperm storage
was deduced from the behaviour of motile sperm in vitro, sperm storage tubule
(SST) history, and the SST epithelial cell ultra structure. Sperm residing in the
SST were considered to be immotile. It is however likely that residence
depends upon the sperm moving against the current generated by the SST
epithelial cells (Froman and Feltmann, 2005).
2.8.2 Behaviour of Sperm in the Oviduct of the Hen
Froman and Feltmann (2005) reported that the hen‟s SST is located
between the vagina and shell gland of the oviduct. Previously, sperm residing
in the SST were considered immotile (Tabatabaei et al., 2009). However, it is
likely that storage depends on moving against a current generated by the sperm
storage tubule epithelial cells (Hafez, 1985). Cockerel spermatozoa are motile
at a body temperature of 41oC for an interval of days to weeks following
ejaculation (Hafez, 1985; Tabatabaei et al., 2009). In turkeys, about 40% of
42
the artificially inseminated semen dose is retained by the hen, the remainder
being expelled through the cloaca. How the sperm enter, survive, and exit these
sperm storage tubules are however, not known. Transport of sperm to the
uterovaginal region is rapid and only viable sperm enter the SST. Current
evidence suggests that the release of stored sperm is episodic, and was first
thought to be associated with oviposition (Hafez, 1985).
Movement of sperm through the oviduct is achieved by smooth muscle
contractions and/or ciliary activity. The sperm accumulate in the mucosal folds
and short tubular glands at the lover end of the infundibulum. At ovulation,
spermatozoa are released (probably by distention of the infundibulum) to
fertilize the ovum (Hafez and Hafez, 2000). According to Hafez and Hafez
(2000) the sperm in mammals spend a relatively short time in the female tract,
while in chickens and turkeys sperm can spend a much longer period of time in
the oviduct before fertilizing the egg yolk cell-up to 32 days in the chicken and
70 days in the turkeys. Although the process of prolonged sperm storage in
turkeys and chickens is not known, it is thought to include a reversible
suppression of respiration and motility of sperm, as well as stabilization of the
plasma membrane and maintenance of the acrosome integrity (Tabatabaei et
al., 2009). According to Mauldin (2000) spermatozoa are released from the
storage tubule to fertilize the sequentially ovulated ova at regular intervals.
After release, the sperm are taken to the ovum by contraction of the hen‟s
oviduct and sperm motility is no longer critical. Within 5 to 10 minutes after
ovulation, sperm have already moved to the germinal disc on the surface of the
43
ovum. The sperm that make contact with the perivitalline layer of the ovum
undergo an acrosome reaction and, presumably by the action of the trypsin –
like enzyme acrosin, which hydrolyzes the perivitelline layer (Myles, 1994).
Theoretically, only one sperm cell fertilizes the ovum, but polyspermy
has been observed in the hen‟s ovum with many holes hydrolyzed in the
perivitelline membrane (Hafez and Hafez, 2000).
2.9 Artificial Insemination in Turkeys
Artificial insemination is a routine practice in the turkey breeder industry. It
was originally implemented in order to control diseases such as Mycoplasma
meleagridis. It has continued as a means of ensuring high levels of fertility (as
much as 95% or more) during the main part of the breeding season when
performed by skilled staff (www. Hybridturkeys.com.2009). Artificial
insemination in the broad sense is a technological process involving semen
collection, processing and artificial deposition of male gamete into the female
genitals to fertilize the oocyte(s) thereby by-passing semen deposition by
natural mating (McDonald, 2003). Although first applied by the chicken
industry, artificial insemination has had its greatest impact in the turkey
industry where all breeder hens are artificially inseminated (Burke, 1984). In
the 1960‟s and 1970‟s, inseminations were based on semen volume per dose. In
the 1970‟s and 1980‟s, inseminations were based on numbers of sperm per
dose; and in the late 1980‟s into 1990‟s, inseminations were based on the
number of viable sperm per dose (Van Wambeke and Huyghebaert, 1989).
Many of the principles and procedures used were adapted from cattle (Wilson,
44
1978). The techniques of semen collection, processing and artificial
insemination have been reviewed by Sexton, (1979), Lake, (1986) and
Dongohue and Wishart, (2000). Pioneers in poultry field were Burrows and
Quinn (1939) who developed the method of abdominal massage and pressure
techniques to collect semen.
The objective of artificial insemination is to deposit optimum number of
normal motile spermatozoa in the female reproductive tract so that they reach
the oocyte at the most favorable time to ensure spermatozoa capacitation and
fertilization of the ova (Hafez, 1985; Bearden et al., 2004).
In developed countries, the wide spread application of artificial
insemination in turkey reproduction is no longer for the purpose of genetic
improvement but because the unnaturally rapid weight gain coupled with their
abnormally configured anatomy puts tremendous pressure on the skeletal
system and vital organs of commercially raised turkeys. The birds commonly
suffer from painful leg and joint disorder, lameness, heart problems and
weakened immune system as well as circulatory system abnormality.
Consequently, the birds have problems of standing and can no longer perform
natural mating (www.factoryfaningFF, 2010). Also, to ensure propagation and
further exploitation of the exotic commercial turkeys, which have been
reported to show high degree of adaptation to Nigerian environment
(Zaharaddeen et al., 2004), the application of artificial insemination is
imperative.
45
2.9.1 Artificial Insemination Techniques in Turkeys
The most reliable and successful routine for insemination in poultry, is
by depositing semen in the mid vaginal area. To achieve this, the vaginal
orifice must be everted by using gentle abdominal pressure (Cole and Cupps,
1977). There are however, two techniques which have been adopted in
inseminating chickens and turkeys. These techniques are:
1. Intra-peritoneal insemination.
2. Vaginal insemination.
Intra-peritoneal insemination: In this technique, a sharp needle is punched
through the abdominal wall and the cannula inserted to deposit semen into the
region of the ovary. Although this technique of artificial insemination is not
reliable, it is occasionally used by farmers (Cole and Cupps, 1977).
Vaginal Insemination: This is the most commonly used artificial insemination
procedure and requires two persons for the operation. For insemination,
pressure is applied to the left side of the abdomen around the vent. This causes
the cloaca to evert and the vagina to protrude so that a syringe or plastic straw
can be inserted into the oviduct and the appropriate amount of semen delivered
(Hafez, 1985). The cloaca is everted by holding the thighs of the hen between
the thumb and the forefingers while the body rests in the palm of the left hand
(Etches, 1996). As the semen is expelled by the inseminator, pressure around
the vent is released, which assists the hen to retain sperm in the vagina or
sperm storage tubule (SST). Due to the high concentration of turkey semen,
hens have to be inseminated for two consecutive days for the first time and
46
thereafter once a week with 0.025ml (2 billion spermatozoa) undiluted pooled
semen for optimal fertility (Etches, 1996).
2.9.2 Advantages of Artificial Insemination
Hammerstedf (2008), noted that natural mating fixes an upper limit of
roosters to hen at a ratio of about 1.10, far below the biological maximum of
1:1000 set by the roosters‟ rate of sperm production. It has been reported that
in flocks of poultry where natural mating is employed, the dominant male,
because of his size may not be the most sexually active and may not allow
other males to mate (Hafez, 1985).
The advantages of artificial insemination are as stated below:
It enhances the use of injured birds: Valuable toms that have physical
inuries in the legs can still be used for artificial insemination
(Sexton,1984).
Artificial insemination improves the egg hatchability and thus decreases
expenses (Omparakash et al., 1992, Figueiuredo et al.,1999).
The method of semen preservation makes it possible to increase the number of
hens inseminated by a particular male.
It is used in accelerating genetic progress (Hafez, 1985).
It is used to overcome periods of low sperm production due to
environmental stress and low libido.
Artificial insemination is used to reduce spread of reproductive pathogens
(particularly mycoplasma).
47
It is used to solve the problem of physical incompatibilities (Sexton,
1984).
To ensure high level of fertility in virgin turkey hens, breeders typically
attempt to follow nature‟s increasing high levels of matings just prior to the
outset of egg production (Mclutyre and Christensen, 1983; McIntyre and
Christensen, 1985; McIntyre et al., 1982; Judd, 2001).Commercially, virgin
turkey hens undergo artificial insemination 3 times in succession, within 3 to 4
days, following outset of egg production, after which hens are inseminated at 7
– 14 days intervals throughout the production period (Brown, 1974; Van Krey
et al., 1976 McIntyre and Christensen, 1985: Ogasawa and Rooney, 1996).
This procedure is thought to fill the sperm storage gland of the hen and prevent
fertility arrest (Verma and Cherms, 1965). Insemination involves the
placement of a predetermined volume (generally less than 0.1 ml) of semen
with a minimum of 100 – 200 million viable spermatozoa within the hen‟s
vagina with a syringe or with mechanical semen dispenser (Hafez, 1983).
2.9.3 Depths of Insemination:
Variations among such artificial insemination techniques as depth of
insemination and time of insemination can influence the rate of fertility (Judd,
2001). Lorenz (1959) recommended deep semen deposition whereas Rooney
et al. (1966) found no fertility differences when inseminating large and Bronze
hens at 1.25cm or 5cm depth. Ogasawara et al. (1968) reported optimal
fertility with insemination > 5cm in which the spermatozoa were placed close
to the sperm storage gland. Also, Biellier et al. (1960) found that deep
48
insemination, (8cm) of Broad Breasted Bronze hen, produced better fertility
compared to 2.5cm depth of insemination. However, WentWorth et al. (1975)
inseminated three different lines of turkeys (Large White Hybrid, Bronze and
Large White inbred) and showed significantly greater fertility at 2cm depth of
insemination compared with 7cm depth of insemination. Contrary to both
Large White lines, the Bronze turkeys did not have consistency in superior
fertility with shallow depth of insemination. Wentworth et al. (1975) stated that
the depth of insemination did not affect the duration of fertility in Bronze hens,
but Large White had a longer duration of fertility following shallow
insemination.
2.10 Fertility in Turkeys
Fertility is a very important measure of reproductive efficiency (Malecki
et al., 2004). This is because production of fertile eggs at economically
acceptable level determines the productivity and sustainability of production
(Keith, 2008). Fertility is considered as the total actual reproductive capacity
of the male and female when mated together to produce individual offspring
(Kamar, 1960). The problem of unfertilized eggs has long been identified as
one of the most critical factors limiting the success of breeding programmes
and ranges from 10.0 – 98.2% both within and between farms (Mushi et al.,
2008; Dzoma and Motshegwa, 2009). Research has shown that as fertility
increases, hatchability improves and a higher number of day-old chicks is
produced (Keith, 2008). In a mid size turkey farm, Bagley (1997) observed
49
that a 1% increase in fertility resulted in an estimated increase of 225,000
poults hatched annually.
2.10.1 Infertility in Turkeys
Low fertility in turkeys is undoubtedly, one of the most important basic
problems facing commercial turkey producers (Keith, 2008;
www.factoryfarmingffFF, 2009). Turkeys are therefore one example of poultry
where the need to enhance the reproductive performance is particularly high
(www.vetsweb.com, 2010) Breeder infertility can be broadly categorized into
hen infertility, mainly involving the failure to lay eggs, inability to retain large
quantity of semen in the sperm storage gland or inability of the hens to retain
sperm for a long time in the sperm storage gland, and male infertility,
involving mainly the inability to supply viable spermatozoa.
2.10.2 Factors that Affect Fertility in Turkey Hens
Factors that influence fertility in naturally mated females and factors that
affect fertility in artificially inseminated females are as shown below:
(a) Factors that influence fertility in naturally mated females:
1. Infertility syndrome
2. Age of the female
3. Mating behavior
4. Body weight
5. Frequency of mating.
6. Genetic make-up of the female.
7. Nutrition
50
8. Diseases
(b) In fertility under artificial insemination: These may be as a result of the
following factors:
a) Deposition and timing of insemination
b) Semen quality
c) Semen dosage
d) Oviductal environment
e) Number of sperm inseminated into the oviduct
f) The reproductive physiology of the hen and the activity of sperm in the
oviduct.
g) Stress
h) Immunity against sperm (Tabatabaei, 2009, Dzoma, 2010).
2.10.2.1 Factors influencing infertility in naturally mated hens
2.10.2.2 Infertility Syndrome
It is a common experience that many females are occasionally sterile
even with good males (Kamar, 1960). Some hens have been found to be
naturally incapable of producing fertile eggs (Burke, 1984). Singh et al. (1964)
reported a condition known as “infertility syndrome”- a sudden, unexplained
decreased fertility in sexually resting breeder hens. Similarly, small amount of
egg lay which is related to a variable propensity toward cessation of egg laying
due to broodiness is also a good example of low reproductive efficiency in
turkey breeder hens (www.vetsweb.com, 2009).
51
2.10.2.3 Age of the Hen
Research results have shown that with advancement in age, the
reproductive performance of breeder hens, starts to decline with marked
increases in body weight and egg weight; decreased egg number and drastic
decline in hatchability; cases of infertility, embryonic mortality and increased
number of cull chicks (Durape, 2007: www.factoryFarmingffFF,2010).
However, a few possible explanations exist as to why drastic infertility occurs
in older hens. Research has shown that the number of sperm residing in the
sperm storage glands of virgin, old and young hen is equivalent. The decrease
in fertility and hatchability with increasing hen age has been attributed to the
following reasons:
1. Sperm are released from the sperm storage glands in older hens more
readily or in larger number than in young hens.
2. Older hens are typically heavier and fatter which may likely reduce the size
of the sperm storage tubules, and so older hens would not store as many
sperm as young hens.
3. Sperm stored in older hens do not retain their viability as long as when
stored in young hens.
4. Older hens produce less receptors sites on the ovum for sperm to bind and
penetrate prior to fertilization (Keith, 2009).
Mating Behaviour in Turkey Hens
Several researchers have reported the characteristic mating behaviour
patterns of turkeys. Carte and Leighton (1968) reported that turkey hens
52
displayed an intense sex drive just prior to reaching sexual maturity, during
which time the reproductive efficiency of toms were very low. It was also
reported that during periods of high egg production, the hen‟s desire to mate
was very low while the mating efficiency of the males was increased. This
inverse relationship has a negative implication on the reproductive efficiency
and has been implicated to be a major cause of differential fertility in turkey
breeder flock, because the hens have been shown to be responsible for the
initiation of mating (Mar golf et al., 1947, Leighton, 1952, and Smyth and
Leighton 1953).The hens have been reported to demonstrate the willingness to
mate by assuming sexual crouch in the immediate vicinity of the male. The
male may mate or ignore the crouching female due to higher preference for
another female (Carte and Leighton, 1969). Preferential mating has also been
reported to be a cause of differential fertility in turkey. Milby and Thompson
(1945) observed that preferential mating in turkeys resulted in some hens
laying few or no fertile eggs. Carte and Leighton (1969) reported preferential
mating in rotated male mating scheme. Females show a reduction in sex drive
following an incomplete mating which is comparable to that following a
complete mating. Trutting activity has been observed in females in which case
some hens court other hens and actually complete mating with some of them
with concomitant loss of libido. Libido in the female is affected by her rearing
environment (whether or not males were present and by her social ranking).
Receptivity (crouching) varies from hen to hen and this affects the chance of
53
successful mating because the female probably determines whether or not the
sexual advances of the male will lead to copulation (Bahr and Bakst, 1985).
Effects of Body Weight of the Hen
Body weight of hens has profound effect on the overall flock fertility in
poultry. When breeder hens are too heavy, reproductive performance suffers as
well as egg production. The possible explanations of this are several. One
relates to the storage of sperm cells in the sperm storage glands. As it was
postulated, when hens become overweight, the excess mass in the abdominal
region may cause the holding capacity of the sperm storage tubules to be
reduced. If these hens, which are already less capable of producing fertilized
eggs, have a reduced ability to store viable sperm cells long term, and cannot
internally store as many total sperm cells, fertility due to age would be
complicated. Additionally, excess body weight whether a function of a larger
frame size or body mass, may decrease the success rate of male mating activity.
Heavier hens do not reproduce as well as lighter hens as they age (Keith, 2009).
Nutritional Causes of Infertility
Nutrition is a vital aspect of animal breeding. Birds, like other animals
need energy to carry out the actual process of mating and also invests some
nutrients in the egg (Dzoma, 2010). In ostrich, egg size, an indicator of
maternal investment (Heaney and Monaghan, 1995), is also a good predictor of
hatching mass as well as chick survival at 1 month of age (Bonato et al., 2009).
Starving hens are also less able to breed while deficiencies of some macro and
54
micro nutrients can adversely affect fertility, hatchability and chick survival
(Dzoma, 2010).
Feeds containing 3200 kcal/kg metabolizable energy and 17% crude
protein are ideal for breeder turkeys (Obioha, 1992; Sotirov, 2002). Feeds
deficient in energy and protein can affect body condition of breeder and can
decrease egg production by as much as 28% (Brand et al., 2003).
Influence of Disease on Fertility:
Good health is an important aspect of reproduction. Many diseases may
result in reproductive failure, either through failure to produce eggs or through
production of abnormal or contaminated eggs (Cabassi et al., 2004). Chronic
diseases such as aspergillosis or avian tuberculosis may cause reduced fertility
even before clinical signs become noticeable (Tabatabaei et al., 2009). Internal
parasites may result in debility directly or via a decrease in the availability of
essential nutrients to the animal (Shanawany, 1999).
2.11.1 Infertility under Artificial Insemination
Researchers have identified a number of factors that cause infertility in
artificially inseminated flock. These factors are as discussed below;
2.11.2 Stress
Stress factors have been noted to affect fertility in breeder flock
(Thatohatsi, 2009). Stress factors of all kinds compromise virtually every
system of the body, producing stress chemicals, which in turn diminish the
function of organs and glands (Durape, 2007). Rough handling of hens during
capture prior to insemination and dropping the hen too hard after insemination
55
have been found to cause infertility in breeder flock (www.ariagen.com, 2009).
Hens must be handled with care during capturing before artificial insemination
and released gently after insemination otherwise semen may be regurgitated
from the vagina. Any degree of stress caused to the bird may interfere with the
transport of the sperm, and have a negative effect on the fertilization rate (Lake,
1983; Donoghue and Wishart, 2000; Obidi et al., 2008).
2.11.3 Oviductal Environment of the Hen
The reproductive physiology of the hen and the activity of sperm in the
oviduct have been implicated to cause infertility in turkeys. Fertility levels after
artificial insemination may be influenced by the effect of the oviductal
environment on the transport of the sperm and the retention of their fertilizing
capacity. Any change in the hen‟s oviduct, either do to environmental or
physiological factors may lead to inexplicable fertility problems. For instance,
changes in environmental temperatures may result in infertility in turkey hens.
A decline in the fertility of hens exposed to high environmental temperatures
could partly be due to inconducive oviductal environment, which may affect
the metabolic activity of the sperm. The start of the decline in fertility of hens
differs with season and type of bird. For instance, in broiler turkeys, fertility
declines sooner than in layer-type turkeys (Lake, 1983; Donoghue and Wishart,
2000).
2.11.4 Immunity against Sperm
Fertility levels in fowls and turkeys bred by artificial insemination may be
affected by the hens generating antibodies against the sperm, causing the sperm
56
to be ineffective. This may result in an occasional decrease in fertility during
the breeding period (Lake, 1983).
2.11.5 Semen Quality
Saacke (1983) stated that semen quality traits have been classified
according to sperm viability or morphology. The morphology of sperm is also
considered to reflect the physiological status of the male for sperm production
and reflects the viability of storage in the yonadal ducks. Viability, as other
semen traits, can reflect the fertility status, but it also measures man‟s
interaction with semen as it is collected, processed and inseminated. Semen
traits related to fertility e.g. sperm motility, velocity, acrosome morphology etc.
may affect the penetration of the cervical mucus and are thus important for
semen preservation and altimately fertilizing capacity (Tabatabaei et al., 2009).
Fertility and the number of stored sperm in the hen‟s oviduct increases with
increasing number of viable and motile sperm inseminated (Tabatabaei et al.,
2009).
2.11.6 Number of sperm inseminated into the oviduct:
A high level of fertility throughout the breeding season can be
maintained by a minimal number of high quality sperm being inseminated at
regular intervals. One insemination per week with 0.025ml containing 200
million fresh sperm will be sufficient to maintain high fertility rate in
commercial turkey flocks (Burke, 1984). The frequency of insemination and
number of sperm inseminated may be increased from the middle to the end of
57
the breeding season to overcome a decrease in fertility at any specific time
(Tabatabaei et al., 2009).
2.11.7 Time of Insemination
More and Byerly (1942) and Malmstrom (1943) showed that chicken
hens laid fewer percentage of fertile eggs if they had a hard-shelled egg in the
uterus at the time of artificial insemination. This suggests that for high fertility,
hens should not be inseminated when a high percentage of them have hard-
shelled eggs in their oviduct. In naturally mated flocks, Gracewski and Scott
(1943) and Parker (1950) observed that fertility of eggs was higher when
mating was restricted to the afternoon as compared with forenoon. Parker
(1945) and Bornstein et al. (1960) reported higher fertility from p.m. than from
a.m. artificial inseminations. To determine the effects of the time of artificial
inseminations on fertility, Parker and Arscott (1970) conducted two
experiments with White Leghorn chickens in which fresh undiluted semen was
pooled from 10 cocks and hens inseminated at 8am, 12noon, 4pm, and 9pm, in
experiment 1 and 3:30pm and 9pm in experiment 2. In experiment 1, it was
observed that fertility at 2 to 9 days following insemination was 79.0%, 91.3%,
96.2% and 95.7% for hens inseminated at 8am, 12noon, 4pm and 9pm
respectively. Fertility from the 8am insemination was found to be significantly
lower than that from the other three groups. With the noon inseminations,
fertility was intermediate and significantly lower than that from the two pm
groups. There was no significant difference in fertility of eggs resulting from
the 4pm and 9pm inseminations. Similarly, in experiment 2 there was no
58
significant difference between 3:30pm and 9pm, inseminations with fertility
being 94.3 and 96.4% respectively. These results of afternoon and evening
inseminations were reported to be in agreement with those reported by
Schindler et al. (1959). Although lower fertility does result from inseminations
carried out when hens are carrying hard-shelled eggs (near the time of
oviposition), turkey hens are inseminated commercially without regard to
ovulatory stage (Burke, 1984; www.FactoryFarmingffFF, 2010).
2.12.1 Infertility in Males
Similarly, breeder factors that influence fertility in the male include:
age, mating behavior, nutrition, body weight, disease, high stocking density,
extreme environmental temperatures, season (Tabatabaei et al., 2009). It is
unclear whether fertility is heritable (Bagley, 1997), but it can be affected by
inbreeding (Dzoma et al., 1995). Inbreeding is known to cause elevated rates
of infertility in domesticated animals, primarily because of homozygous
expression of recessive lethal alleles (Thornhil, 1993).
2.12.2 Body weight of Toms
Body weight of toms is important when selecting for breeding flock
performance. A significant negative correlation has been established between
the growth rate or body weight and the reproductive performance in males
(Harris et al., 1980; Lukaszewicz and Kruszynski, 2003). It is crucial for the
males to reach a maximum body weight typical for a given breed, strain or
type, before being used for breeding (Lisowski and Bednarczyk, 2005). The
number of sperm per ejaculate and body weight are positively correlated and it
59
may be said that body weight is a good predictor of semen attribute in males
(Tabatabei et al., 2009). In breeder flock, there is an advantage of obtaining
proper male body weight. Too light a male will cause serious problems
reproductively due to low sperm production. In commercial broiler breeder
flocks, it has been reported that flocks with over weight males do not perform
as well as those flocks where body weight has been kept under control.
Although older males are physiologically capable of producing high level of
fertility, they tend to lose the physical attributes to effectively mate breeder
hens as often as necessary. The reduction in the physical capacity to mate may
be caused by sore legs and feet which restricts the mobility and balance
necessary to successfully complete matings, (Keith, 2009).
2.12.3 Age
It has been documented that as males age, there is a decline in fertility
which is associated with a reduction in the number of spermatozoa in the
ejaculate and the volume of semen produced (Keith, 2009). Similarly, with
advancement in age, breeder toms show marked increase in body weight,
reduced libido, lower semen volume as well as reduced number of
progressively motile sperm (Bakst and Cecil, 1992; Kelson et al., 1996). Thus,
breeder males are rarely used for breeding after the first year of semen
production (Www.Factoryfarming FF, 2010).
2.12.4 Male Mating Behaviour
Similarly mating behaviour patterns of toms have been found to cause
infertility in turkey breeder flock. For instance, masturbation, evidenced by
60
treading or rubbing the copulatory organ on the floor or against the side of pen
is usually observed in males during which time, they void semen and complete
mating act (Carte and Leighton, 1969). These males eventually lose libido and
are unable to consummate mating available to them. Certain toms commonly
display inefficient mating habits such as mounting the copulatory organ on the
wings or other parts of the hen‟s body. This however, reduces mating
efficiency, which is expressed as a percentage of the initial or the total
available matings completed, or as the percentage of attempted matings
completed (Carte and Leighton, 1969). The correlation between mating
efficiency and fertility was found to be + 0.70 + 0.15 (p < 0.01). Thus, as
would be expected, fertility increases as the number of completed mating
increases. The availability of several sexually receptive hens in a pen tends to
reduce mating efficiency in turkey breeder flock due to male indecisiveness.
Although male rotation in the absence of preferential mating improves fertility
and allows each male an equal chance to mate with each female during the
breeding season, experiments have shown that males vary in their ability to
induce mating receptivity in the females during the breeding season (Carte and
Leighton, 1968).
Other factors might also be logically associated with infertility in
turkeys. For example, genes determining body weight could be linked with
genes causing infertility (Hafez, 1985). In addition, homeostatic mechanisms
associated with reproductive fitness could contribute to the problem (Carte and
Leighton, 1969, McDonald 2003). Lerner (1954), Hafez, (1984) and Keith,
61
(2008) have reported that when intense selection is applied over several
generations, the balance between reproductive fitness and certain traits under
selection are altered. Consequently, only those parents capable of reproducing
contribute progeny to the subsequent generation while unproductive individuals
tend to be eliminated from the population. This difficulty has been
circumvented, in part through artificial insemination because individuals that
will be unfit under natural mating conditions have continued to contribute to
gene pools of various strains of turkeys (Carte and Leighton, 1969).
2.13 Hatchability in Turkeys
Hatchability denotes the percentage of fertile eggs that hatch
successfully following an appropriate incubation period, which is about 28
days in turkeys (Dzoma, 2010). Hatchability is expressed as the number of
offspring hatched divided by the number of fertile eggs at candling (Wilson,
2008). Hatchability therefore, basically involves losses owing to embryonic
mortality at various stages of development (Dzoma, 2010). Various
hatchability results have been reported, ranging from 58% to 100% in turkeys
under intensive management system (Donoghue et al., 2009). Many factors
influence the development of avian embryos. Some of these factors are
environmental while others are associated with the characteristics of the egg
itself (Wilson, 2008).
The environmental factors most often considered are:
3 Temperature
4 Relative Humidity
62
5 Oxygen concentration in the incubator
6 Carbondioxide concentration in the incubator
7 Egg storage condition during incubation and egg handing
8 Disease
9 Turning of the eggs
10 Egg shell characteristics and egg shell quality
11 Incubator setting and peculiar egg characteristics
12 Genetic factor (Burke, 1984: Obioha, 1992, Dzoma, 2010).
Other factors that affect hatchability have been reported to include fertility,
incidence of double yolked eggs and egg size (Obioha, 1992, Dzoma, 2010).
2.13.1 Influence of Temperature on Hatchability.
The incubation temperature for turkey eggs is 37.5oC (Judd, 2001).In
ostrich, the incubation temperature is 36.5oC (Stewart, 1996; Hassan et al.,
2004). These researchers noted an increase in the number of dead-in-shell
embryos and total number of dead embryos when eggs are incubated at 37.5oC.
French (1997) reported that towards the end of incubation, the temperature
inside the egg rises by 2.0oC above the surrounding air temperature, as a result
of metabolic heat production by the embryo. This may result in the death of
the embryos due to hyperthermia, when the same incubation temperatures are
maintained throughout incubation (Meir and Ar, 1990; Hassan et al., 2004).
Ideally, incubation temperatures should be controlled during incubation,
decreasing slightly as the embryo develops (Deeming, 1993).
63
2.13.2 Relative Humidity
The incubation humidity for turkey egg is 60% and this humidity
enables the eggs to lose weight through moisture loss which is an important
determinant of hatchability (Nahm, 2001). In ostrich, at incubation humidity of
25 – 40%, the eggs lose between 12 and 15% of their original weight to
enhance hatchability (Christensen et al., 1996).
2.13.3 Egg Shell Characteristics
Egg shell characteristics play important role in determining hatchability
(Dzoma, 2010). During development; oxygen, carbondioxide and water vapour
are transported into and out of the eggs through pores in the egg shell (Obioha,
1992). The ability of the egg to lose moisture therefore depends on such
parameters as shell porosity, shell thickness and egg size (Gonzalez et al.,
1999). Excessive porosity of the egg shell will lead to excessive loss of
moisture from the eggs and spoilage due to entry of pathogens into the egg.
Excessive moisture loss above 18% puts chick hatching from such egg at
higher risk of dying before day 28 of incubation (Cloete et al., 2001). Low
porosity will limit oxygen consumption and hence cause embryo death
(Obioha, 1992). Eggs with increased thickness have poor hatch (Dzoma,
2010). Egg size and weight have been shown to influence hatchability. Large
eggs have problems of losing the required amount of water, reduced oxygen
uptake and are consequently associated with oedema chicks (Bonato et al.,
2009).
64
2.13.4 Disease/Egg Contamination
Egg contamination can be lethal to the embryo even at low doses
(Dzoma, 2010). The degree of yolk contamination is influenced by the degree
of egg contamination before egg setting (Cabassi et al., 2004). Mushi et al.
(2008) observed a 7.3% hatchability depression associated with microbial
contamination of eggs. Microbial contamination of eggs can result from the
dipping or washing of eggs in liquid disinfectants before setting them into the
incubators. This possibly leads to the disruption of the protective cuticle of the
egg shell (Richards et al., 2002). As a result, eggs should be routinely
fumigated before setting in the incubator (Mushi et al., 2008). Various
microbes have been associated with egg contamination and they include,
bacteria (Escherichia coli, Aeroniounas spp., Bacillus licheniformis,
Enterobacter spp) and fungi (Penicillium spp, Fusarium spp) (Cabassi et al.,
2004, Mush et al., 2008).
2.13.5 Egg Storage
Storage of eggs also affects the hatchability of fertile eggs. Fertile eggs
deteriorate in quality after four days of lay. Under tropical conditions, the rate
of deterioration is faster especially if the eggs are not stored in a cold room
(Obioha, 1992). Research reports have shown that if eggs are stored for more
than a week, there is increased occurrence of embryonic abnormalities and
mortalities due to the degradation of viscosity of the egg albumen (Dzoma,
2010). In the tropics hatching eggs should not be stored beyond 4 days unless
65
they are wrapped in light polythene material, and even then, not beyond 6 days
after laying (Obioha, 1992).
Temperature, humidity, gaseous environment and the orientation or
positional changes of the eggs during storage affect hatchability and chick
quality during incubation. Research reports suggest that prolonged pre-
incubation storage over 14 days have a negative effect on hatchability and
chick survival post hatching (Obioha 1992; Keith 2008). Short time storage (4
days) of eggs between laying and incubation has been shown to give the
highest hatching potential (Reis and Soarers, 1997).
2.13.6 Nutrition
Hatchability can be affected by poor nutrition, especially that involving a
deficiency or imbalance of mineral and vitamins (Perelman et al., 2001).
Nutrient deficiencies in the hens‟ diet can increase embryo mortality.
2.13.7 Age of Hens
Available research reports show that egg size and poor egg shell quality
increase with increasing hen age (Obioha, 1992). Egg size and poor shell
quality have a positive correlation with poor hatchability (Dzoma, 2010).
2.13.8 Incubator setting and peculiar egg characteristics
With continued striving to obtain maximum reproductive efficiency,
more critical appraisal of incubation techniques has been made (Hafez, 1985).
It has been shown that eggs lose water throughout incubation. The amount of
water lost is affected by the number of pores in the shell, pore diameter, pore
length, and moisture level in the incubator. Shell characteristics have been
66
found to vary a great deal from hen to hen, between strains of hens and with the
length of time the hens have been laying (Halawani et al., 1988). It has been
shown that improved hatchability can be achieved if incubator moisture levels
are altered on the basis of shell conductance of eggs being incubated. This is
because during the first 18 to 19 days of incubation in chickens and the first 25
to 26 days in turkeys, the exchange of oxygen and carbon dioxide between
embryo and the atmosphere takes place via chorioallantoic blood vessels
underlying the shell. Before lung ventilation, the exchange of these gases
depends on shell pore characteristic and on partial pressure differences between
the embryo‟s blood gases and the atmosphere (Burke, 1984). Research
findings by Halawani et al., (1988) showed that embryonic mortality in chicken
and turkey eggs tends to follow a well-defined pattern. According to the
authors, the first peak in embryo mortality is noted at about 3 to 4 days of
incubation, and the second occurs at the time lung ventilation begins. The
early mortality peak, which represents about 2 percent in broiler chicken eggs,
is often attributed to chromosomal abnormalities. The late peak representing
about 2.5 to 3.0 percent in broiler chicken eggs, may be due to failure of the
critical organs and systems to mature synchronously. These peaks have been
found to be somewhat smaller in embryos of commercial egg-laying chickens
and somewhat larger in turkeys.
2.13.9 Genetic Factors Affecting Hatchability
The effects of many specific genes that produce gross physical
abnormalities and cause death of chicken and turkey embryos have been
67
identified. Burke, (1984) reported that genetic selection for improved
hatchability may be employed to eliminate embryonic mortality in chicken and
turkeys. Parthenogenesis – the development of unfertilized eggs has been
implicated to account for more than 40 percent of embryonic mortality in
experimental turkey flock (Hafez, 1985).
The hatchability of turkey eggs as a general rule declines after the 9th
to
12th
week of the breeding season (Dickens et al., 1941; Atkinson et al., 1955;
Jensen et al., 1956). Declining hatchability of fertile eggs is usually
accompanied by a decline in fertility (Cooper et al., 1960)
2.14 Candling and Egg Breakout
Eggs are candled by passing an intense beam of light through each egg
to observe, whether it is clear (infertile) or to highlight vascular development of
the embryo in fertile ones. Candling is also used to identify eggshell
abnormalities and dead-in shell problem and is usually carried out at 10days of
incubation (Dzoma, 2010). This procedure is used to establish fertility, which is
the number of living embryos divided by the total number of eggs candled
(Hafez, 1985). Eggs are deemed to infertile when candling results at 10 days of
incubation show an apparent lack of embryonic development (Ley et al., 1986).
However, such cases may be difficult to distinguish from eggs, whose embryos
died early in the incubation period, generally referred to as early Embryonic
Death, because in both cases, the candling results may be similar. When early
Embryonic Death eggs are opened up, an embryonic disc, which is absent in
infertile eggs, can be seen floating (Hicks, 1993). Reproduction in breeders is
68
usually evaluated in the hatchery as part of an egg candling and egg breakout
programme (Keith, 2008). Results of an egg candling and breakout programme
reveal flock-by-flock patterns and fluctuations in embryonic mortalities,
fertility, hatchability, and contaminations (Wilson, 2008; Keith, 2008). It is
however important to candle eggs between 10 – 18 days of incubation and open
the eggs after incubation to determine percentage fertility and early dead
embryos. While the end results of low fertility or high numbers of early dead
embryos are both low hatchability, the causes are distinctly different (Wilson,
2008).
High early embryonic mortality is usually related to poor egg handling,
flock health or chemical exposure. Gathering and using candling and egg
breakout data to correct low fertility, high embryo mortality, upside down
placement or loss due to high cracked egg numbers are critical in maximizing
chick production (Wilson, 2008; Keith, 2008).
2.15. Systems of Turkey Management
Low percentage hatch of eggs produced by turkeys constitutes a major
problem to turkey farmers. The seriousness of the problem is increased by the
variability in hatching results observed from year to year by individual
producers. Marked differences in percentage hatch are also noted on different
farms where the same feed is used and breeding stock from the same source is
kept. Such variability may indicate that factors of management influence
fertility and hatching results to a considerable extent (Robb lee et al., 1956).
69
Rearing systems and nutritional management practices have however
been employed to bring about statistically significant increase in reproductive
performance of turkeys such as increase in ovulation (for hens), increase in the
number of eggs laid (for hens), increase in egg mass (for hens), delayed onset
of photo refractoriness and increase in semen quality (high sperm viability,
high sperm concentration, higher sperm motility, an increased ratio of viable to
non-viable sperm), and enhanced binding of sperm to the periviteline
membrane, (www.patentstorm, 2009).
2.15.1 Rearing Systems in turkey production
The local turkeys are naturally foragers and can be kept entirely as
scavengers (Peters et al., 1997). NRC (1991) reported that these sleekly built
turkeys can be reared virtually any where and that their natural habitats are
open forest and wooded area. However, urbanization and the pressure on the
land for crop production pose a threat to this no-cost extensive system of
production. Their exotic counterparts have been highly selected and
genetically programmed for fast growth in order to maximize production and
can no longer survive without human care (ww.factoryFarmingffFF, 2010).
Today‟s turkeys are reared under two major management system:
1. Semi – intensive system
2. Intensive system
2.15.2. Semi – Intensive Management System
The semi – intensive management system is the system usually adopted
by most small – scale rural and Peri – urban turkey farmers. Under this system,
70
feed, medication and simple shelters are provided. This system is not very
common in commercial operations but may appeal to farmers who have large
compound and surplus land or to mixed farmers who may dump the after
harvest wastes, husks and other refuse into the runs to minimize the feeding
cost (Obioha, 1992).Under this system both toms and hens run together in the
runs and the hens corralled when they begin to lay eggs so as to protect them
from predators. Eggs may be gathered to prevent broodiness and thereby
increase egg production. Farmers may hold hatching eggs for several days and
then may place them under a chicken hen for incubation (certain chicken hens
can be used this way to hatch turkey eggs). Farmers who keep exotic “broiler”
type turkeys in rural and peri – Urban areas usually confine them in backyards
with fences and hatch their eggs in incubators. Some turkey farmers
particularly hobby or backyard farmers, find it cheaper and more convenient to
hatch the fertile eggs by natural means using broody hens (Obioha, 1992). This
adversely affects egg production as the hens normally do not lay egg during the
periods of brooding and raising of her poults. Generally, rural farmers who
subscribe to natural incubation in open farm lands usually experience lower
egg hatchability, high chick and hen mortality during the rainy season than the
dry season. This is because during rainy season, hatching eggs and brooder
hens are exposed to rain fall, snake and soldier ants which damage the eggs and
kill the hens.
71
Advantages of the Semi- Intensive System:
The semi – intensive management system has been reported to have the
following advantages:
1. It reduces the cost of feeding by fifty percent
2. Mortality may be lower because of dispersal of the birds
3. There is significant saving on building cost
4. Capital investment is low
5. The cost benefit ratio is high (Milby, 1960, Obioha, 1992, CPDO,
2008).
2.15.3 Nutritional Management under Semi-Intensive System
Under the Semi-intensive management system, the birds scavenge for
fresh forages, snails, corns, insects and worms. The farmers supply additional
water, kitchen scraps and farm wastes, as well as supplements (cereal grains,
PKC etc, to meet their nutritional requirements. This system has been reported
to increase vitality in turkeys by creating room for exercise (Milby, 1960). It
also furnishes the birds with varieties of succulent forages and other potent sex
enhancing plants which improve semen quality, fertility and hatchability
(Durape, 2007). The growth performances of semi-intensively managed and
intensively managed turkeys have been compared (Milby, 1960). Turkey
growers have reported that semi-intensive reared turkeys grow as well as the
confined turkeys. Payne (1959), found little or no differences in growth
between ranged and confined turkeys; differences in their feed efficiency were
modest (about 4% in favour of ranged group). Wyne et al. (1959) fed high
72
energy supplement diet to toms on range and reported higher weight gain for
toms on range than the confined group on compounded diet. To further
demonstrate the efficacy of range plants on semen quality and fertility
parameters, Durape (2007), fed herbal formulations to groups of confined
broiler breeder flock and compared their results with a control flock. He
reported higher value for percentage fertility for the treatment group than the
control group.
Similarly, Durape (2007) reported that phytochemicals from range plants have
significant stress- fighting powers which minimize the damaging effects of
stress on semen quality and quantity.
There is however, lack of information on the effect of rearing system on
semen quality, fertility and hatchability of turkeys under range condition and
semi-intensive management system.
2.16 Intensive Management System
The decision to make turkey meat available to consumers throughout the
year has led to the development of housing facilities for precise environmental
control: heating, ventilation and lighting. These facilities are designed to
provide sufficient oxygen for normal growth and development of the turkeys
and to remove excess ammonia, carbon dioxide dust and moisture (Nathan and
Kessler, 2008). In confinement rearing (intensive management), the turkeys are
housed in permanent buildings and are not allowed to go out doors to get feed,
water or to lay eggs. All requirements are provided within the building. Under
this system, feeding is ad libitum (Obioha, 1992). Obioha (1992) reported the
73
nutritional requirements of intensively reared turkeys of various ages in the
tropics as shown in Table 10 below:
Table 10: Recommended nutrient allowance for poultry under tropical climatic
condition
Nutrient
Turkey Pre-
starter
Turkey
starter
Turkey
Grower I
8-16 Wks
Turkey
Grower II
16-20 Wks
Turkey
Finisher
Crude Protein %
Crude Fibre %
Met Energy (Kcal/kg)
Calcium %
Phosphate %
Sodium %
Potassium %
Magnesium %
Iron mg.
Copper mg.
Manganese mg.
Zinc mg.
Lysinc %
Methionine %
Leucine %
Meth + Cystine
Typtophan %
Isoleucine %
Theonine %
Arginine %
Phenylalanine %
Baline %
Vitamin „A‟ I.U.
Vitamin „D‟ I.U.
Vitamin „B12‟ mg
Thiamine mg.
Riboflavin mg.
Panthotenic Acid mg.
Pyridoxine mg.
Niacin mg
Choline mg.
Vitamin „E‟ I.U.
Vitamin „K‟ I.U.
Biotin mg.
26.0
5.5
2800
1.25
0.90
0.15
0.42
0.06
65
6.0
40
75
1.70
0.55
1.80
1.00
0..25
1.00
1.00
1.50
1.00
1.15
4000
850
0.005
2.20
3.50
10.00
2.00
70
2000
12.00
2.00
0.20
24.0
5.5
2900
1.20
0.85
0.15
0.40
0.05
60
6.0
40
75
1.60
0.50
1.70
00.85
0.24
0.95
0.95
0.85
0.85
1.10
4000
850
0.005
2.20
3.50
10.00
2/00
70
2000
12.00
1.50
0.20
20.0
6.0
3000
0.80
0.65
0.10
0.35
0.05
40
5.0
35
40
1.20
0.35
1.40
0.70
0.19
0.80
0.70
0.75
0.75
0.85
4000
850
0.00
2.00
3.00
9.00
2.50
60
1100
10.50
1.00
0.10
17.0
6.0
3200
0.80
0.65
0.10
0.35
0.05
40
5.0
35
40
0.80
0.28
1.00
0.52
0.14
0.60
0.52
0.55
0.55
0.65
4000
850
0.003
2.00
3.00
8.50
2.50
50
1100
10.00
0.80
0.10
15.0
6.0
3300
0.80
0.70
0.15
0.40
0.05
60
4.0
35
60
0.60
0.25
1.50
0.40
0.12
0.50
0.40
0.55
0.45
0.55
4000
850
0.003
2.00
3.50
12.00
2.00
30
1000
20.00
1.00
0.15
2.16.1 Nutritional Management of Turkeys Under Intensive System
Earlier methods of feeding turkeys were free-choice system wherein the
turkeys were allowed to balance their own diet with continuous access to
74
protein – vitamin – mineral concentrates and whole grains (Massey and Fuller,
1961). However, some modifications of this method were practiced by limiting
one or the other component when over consumption of either energy or protein
occurs (Massey and Fuller, 1961). Earlier reports indicate that turkeys are best
fed with either pelleted feed or mash feeds Proponents of all mash feeding
insist that when all the components are mixed in a prescribed ratio, scaled to
the changing requirements of turkey throughout the growing and breeding
periods, growth rate, feed efficiency and reproductive performance are
improved (Massey and Fuller 1961). Blaylock et al. (1954) studied the effect
of feeding high and low energy pellets with corn and barley to turkeys from 8
to 23 weeks of age. They found no differences in weight gain among treatments
but the greatest feed efficiency was obtained when high energy, low fiber
pellets were fed. Carter et al. (1957) tested various fats and protein levels in
both small and large type turkeys and concluded that type of turkey will
influence the protein requirements, suggesting the need for formulating feeds
for turkeys according to their size and type. Day and Hill (1957) found that
varying the protein level within isocaloric diets had no effect on growth or feed
efficiency of turkeys from 8 to 12 and 12 to 16 weeks of age. Increasing the
energy level resulted in proportional increase in feed efficiency and an
improvement in growth in the 8 to 12 weeks period. Scoft (1956) suggested
changing the diet at four week intervals with a progressive decrease in protein
and increase in productive energy. Couch (1958) advocated the use of all-mash
complete feed programme, which varied from 30% protein at the start to 16%
75
protein after 17 weeks of age. He suggested caloric -protein ratios of 42 to 45:
1 from 11 to 16 weeks and 60 to 70:1 thereafter. Recent research reports have
shown that protein level is a limiting factor in the diet of turkeys (Sotrirov et
al., 2002). Optimal protein content is a prerequisite not only for a rapid growth,
but also for the normal condition of breeder toms by influencing both
quantitative and qualitative semen parameters. It has been shown that low
dietary protein content (12.8%) decreases semen quality (Cherms et al., 1981;
Brown, 1982; Cecil, 1986; Cecil, 1986; Dobrescu, 1986; and Sexton et al.,
1986).
Similarly, Sotirov et al (2002) fed 14% and 17% protein diets to breeder
toms and concluded that higher dietary protein content improved the
quantitative and qualitative semen parameters as well as the different lysozyme
concentrations in the blood, which has significant influence on spermatozoal
motility as well as live spermatozoa. In a comparative study between local
turkeys and White Nicholas turkeys, Zaharaddeen et al. (2005), fed a 10%
crude protein diet and obtained lower values for ejaculate volume, sperm
concentration, live spermatozoa, abnormal spermatozoa and total sperm in
ejaculate for local toms. Semen quality parameters of local turkeys under
intensive management system are shown in Table 11.
Table 11: Semen quality parameters of local turkeys under intensive management system
Semen parameter Mean Value (±SE)
Volume (ml) 0.11±0.43
Progressive motility (%) 84.25±2.23
Sperm concentration (x 109) 2.80±166.03
% live spermatozoa 83.50±2.82
% abnormal spermatozoa 14.33±1.56
Total sperm in ejaculate (x 109) 47.04±23.15
76
Sotirove et al. (2002) fed exotic toms formulated diets containing 14% and
17% crude protein respectively and reported their semen quality results as
shown in Table 12 below
Table 12: Semen parameters of turkeys fed with different protein levels
Semen parameters
Groups in respect to protein levels
14% 17%
Ejaculate volume (cm3) 0.178 0.210
Sperm concentration ( x 109) 3.452 3.611
Sperm motility (%) 63.513 72.339
Abnormal sperm (%) 10.025 10.620
Live sperm (%) 79.023 80.856
Dead sperm (%) 21.043 19.059
Lysozyme in sperm (μg/ml) 7.382 6.304
Lysozyme in sera (μg/ml) 0.207 0.263
2.16.2 Vitamins and Minerals Requirements of Turkeys
It is likely that all vitamins needed for growth and maintenance are also
needed for reproduction (Bearden et al., 2004). A deficiency of vitamin A has
been reported to adversely affect reproduction in both males and females. In
males, vitamin A aids in vision and in the development of the epithelial tissues
lining the digestive system, respiratory and reproductive tracts. Its deficiency
can reduce or even stop spermatogenesis in males. In females, a deficiency of
vitamin A has resulted in an array of reproductive problems such as, repeated
breeding, and weak or dead offspring. Main sources of vitamin A are yellow
corn, green forage etc. Vitamin E (anti-sterility Vitamin) enhances normal
reproduction, improves hatchability and serves as antioxidant in males.
77
Deficiency of vitamin E results in testicular degeneration and sometimes to
permanent sterility as well as nutritional encephalomalacia. In females,
deficiency of vitamin E results in death and lowered hatchability in poultry.
Major sources of vitamin E are cereal grains, oil seed cakes and forages. Other
vitamins that aid in hatchability include Pantothenic acid, Cobalamin, and
Riboflavin (Obioha, 1992; Bearden et al., 2004).
2.16.3 Minerals
Requirements of most minerals are increased per unit of body weight
due to gestation, lactation and growth. If such minerals as calcium, phosphorus,
iodine, copper, zinc, cobalt etc are supplied in sufficient quantities and ratios
productivity and normal reproductive performance of the animal will not be
affected. Reproductive problems have resulted in areas where deficiencies of
specific minerals in the soil have reduced and are not found in natural
feedstuffs. Diets deficient in phosphorus will depress appetite and delay
puberty in poultry. Phosphorus-deficient diets result in rough feathers, poor egg
shell quality, poor bone development and depraved appetites. Iodine
deficiency has been reported to cause a number of reproductive disorders
which include delayed development of the reproductive tract, impaired
embryonic growth as well as poor hatchability in poultry. In males, iodine
deficiency has been associated with low libido and poor semen quality
(Bearden et al., 2004). Copper and cobalt deficiencies have been associated
with low fertility, abnormal embryonic development, and poor hatchability in
poultry. Deficiency of magnesium has been associated with low fertility.
78
Deficiencies of zinc have resulted in impaired spermatogenesis and
testosterone production, poor hatchability, poor bone formation and high chick
mortality (Bearden et al., 2004; Obioha, 1992).
79
CHAPTER THREE
MATERIALS AND METHOD
3.1 Location of the Study
The study was carried out at the Poultry Unit, Department of Animal
Science Teaching and Research Farm, University of Nigeria, Nsukka. Nsukka
lies in the Derived Savannah region, and is located on longitudes 6o 25
‟‟N and
Latitude 7o 24
‟‟E (Ofomata, 1975), at an altitude of 430m above sea level
(Breinholt, et al, 1981). The climate is a typical humid tropical type with a RH
range of 56.01 – 103.83%. Average diurnal minimum temperature ranges from
22oC – 24.7
oC while the average maximum temperature ranges between 33
oC –
37oC (Okonkwo and Akubuo, 2007; Energy Centre, UNN (2008). Annual
rainfall ranges from 1567.05 mm to 1846.98 mm (Meteorological centre, Crop
Science Department University of Nigeria, Nsukka, 2009. Unpublished).
3.2 Plan of the Study
The experiment was conducted in two separate trials: Trial 1 (physical
characteristics of semen) and Trial 2 (fertility and hatchability evaluation) as
influenced by two rearing conditions and different frequencies of semen
collection. Each of the experiments was set in a 2 x 4 factorial with statistical
model as stated below:
Statistical Model for Experiment 1:
Yijk = + i + j + ()ij + ijk
Where
Yijk = Individual observation of dependent variables
80
= Overall mean
i = Effect of management condition on ith individual males
j = Effect of frequency of semen collection on the jth individual males.
()ij = Interaction effect of management conditions and frequency of semen
collection on the ith and jth individual males.
ijk = Random error associated with observation
Statistical Model for Experiment 2:
Yijk = + i + j + ()ij + ijk
Where
Yijk = Individual observation of dependent variables
= Overall mean
i = Effect of management condition on fertility and hatchability on ith
individual females
j = Effect of frequency of ejaculation on fertility and hatchability of jth
individual females
()ij = Interaction effect of management conditions and frequency of semen
collection on the ith and jth individual hens.
ijk = Random error associated with the observation.
3.3 Duration of the Study
Experiment I lasted for 5 weeks in the months of April and June 2009
while experiment II lasted for 16 weeks (from July to October, 2009).
81
3.4 Procurement and Management of Experimental Animals
A total of 72 local type turkeys comprising 24 males and 48 females of
the same age were used for the study. The birds were sourced from a
commercial farmer at Ekwulobia, Anambra State at 8 weeks of age. The poults
were weighed to determine their initial body weight which ranged from to
0.1kg to 0.5kg. The poults were reared together in well-ventilated netted
pens and fed commercial growers‟ mash with clean fresh water ad libitum up to
20 weeks of age. Routine vaccination programmes were observed. At the
twentieth week, the males were randomly divided into two management groups
– intensive management (Group 1) and semi-intensive management (Group 2)
respectively with 12 toms per group. All the males in both groups were
randomly selected, wing tagged and assigned to four frequencies of semen
collection respectively (3toms per collection frequency). At this age, group 2
toms were withdrawn from the commercial diet and subjected to free-range
management in a fenced area of the farm and fed with supplements made up of
maize chaff and PKC. The distribution of experimental toms to treatments is
presented in Table 13.
Table 13: Distribution of Experimental Animals to Treatments
Factor A (Ejaculation frequency)
Factor B
(Management
System)
Groups No. of
males
Control X1 X2 X3 X4
1 Intensive 12 3 3 3 3
2 Semi- Intensive 12 3 3 3 3
82
The feeders for free range toms were positioned at strategic locations in
the runs. They were fed in the mornings and evenings with plenty supply of
fresh clean water in line with management method adopted by rural farmers.
Group A toms continued with the commercial growers‟ mash up to the twenty
sixth week of age during which time they were fed breeder diet containing 17%
crude protein and 12.16 MJ/kg energy until the end of the experimental period.
The females in group 2 were separated from the males at eighteenth week of
age, and fed the breeders diet as the Group 2 toms until the end of the
experimental period.
At the twentieth week of age, the hens were wing- tagged and randomly
divided into two treatment groups – 1 and 2 corresponding to those of the
males. The two hen groups were randomly selected and placed individually in
well ventilated netted pens of 5ft x 5ft dimension The floors were covered with
high absorbent litter material. Trap nests for egg laying were provided in the
pens. The nutrient composition of the breeder diet is as shown in Table 14.
Table 14: Nutrient Composition of the Breeder Diet per 100kg
Ingredient Kg
Maize 42.50
Cassava chips 11.0
Wheat offal 5.00
Groundnut cake 23.00
P.K.C 10.00
Palm Oil 2.00
Limestone 1.50
Bone meal 4.00
VMP 0.25
Salt 0.25
Lysine 0.25
Methionine 0.25
Calculaed Values
Metabolizable energy 12.6MJ/kg
Crude protein 17.01%
Crude fibre 5.42%
83
3.5 Pre-Experimental Period/Training of Toms for Semen Collection
At the age of thirty weeks (Donoghue et al., 1999), all toms in each
group were trained for semen collection three times weekly for three weeks
using abdominal massage technique as described by Burrows and Quin (1937)
and modified by Hybrid Turkeys Co.(www.hybridturkeys.com, 2008).
3.6 Data Collection: Experiment I (Physical Examination of Semen)
The layout of Experiment 1 is presented in Table 15 below. Experiment
1 was performed using 24 toms randomly distributed to the management
conditions – 1 and 2 with 12 toms in each group. In each group (management
condition), three toms were randomly assigned to each of the four frequencies
of semen collection (once, twice, thrice and four times per week) as shown in
Table 15 below. Ejaculates were instantly assessed after collection per male.
Table 15: Lay out of experiment 1(semen evaluation)
Factor B (Frequency of semen collection)
Factor A
(management
method)
Total
no of
toms
Control
(X1)
Once/week
X2
Twice/week
X3
Three
times/week
X4
Four times/week
Intensive 12 (Thursdays)
(3)
(Wednesdays
and
Saturdays)
(3)
(Tuesdays
Thursdays
and Saturdays
(3)
(Mondays
Wednesdays
Fridays and
Sundays (3)
Semi-
intensive
12 (Thursdays)
(3)
(Wednesdays
and
Saturdays)
(3)
(Tuesdays
Thursdays
and Saturdays
(Mondays
Wednesdays
Fridays and
Sundays (3)
Numbers in parenthesis indicate number of toms per treatment
84
3.7 Semen Quality Parameters Measured
Semen Colour
The colour and consistency of the raw semen were determined as
described by Bearden et al. (2004). Only creamy white samples were analyzed
while soiled and coloured samples were discarded.
3.7.1 Volume
The volume of the semen was determined with the aid of a 10ml beaker
and 1ml tuberculin syringe. Each ejaculum was milked into an insulated 5ml
beaker and then aspirated into the tuberculin syringe. The syringe was taped
gently to expel air bubble trapped during aspiration and the volume recorded in
ml.
3.7.2 Progressive Motility
Progressive motility was determined using the method described by
Bearden et al. (2004) and Hafez, (1984). Raw semen sample was pepetted with
a glass pipette and a drop added to 1ml of warm 0.9% physiological saline.
The semen and the diluent were gently but thoroughly mixed by back and forth
swirling for a few minutes. A drop of the diluted semen was placed on a clean
pre-warmed microscope slide; it was clipped under a light microscope and
viewed at (x400) magnification. The percentage motile sperm was determined
by subjective scoring from a range 0 – 100% (Gamal and Kamar, 1959;
Bearden et al., 2004).
85
3.7.3 Dead and Live/Normal and Abnormal Spermatozoa
The percentage live and dead spermatozoa were determined by
differential staining technique as described by Bearden et al. (2004). A drop of
diluted semen sample was placed on a clean dry slide with a stirring rod and
two drops of eosin-negosin added to it with a dropper. A smear was made by
placing a warm slide over the first, spreading the mixture evenly by pulling the
two slides apart and placing quickly on a warming device to prevent cold shock
as the two slides dry.
The slides were clipped to a light microscope and observed at x 400
magnification for the number of live and dead sperm. Spermatozoa, which
picked up the stain were considered dead while those that exuded the stain
were considered alive. 100 sperm cells were counted in each slide and
classified as alive or dead at the time of staining. The live and dead sperm were
reported in percent. On the same slide prepared for live and dead spermatozoa,
the morphologically normal and abnormal sperm were determined by counting
100 sperm in each slide and classifying morphological abnormalities. Values
obtained were expressed in percentage. The abnormal forms considered were
head, tail, and mid piece abnormalities.
3.7.4 Sperm Concentration
Sperm concentration was determined with a haemocytometer as
described by Bearden et al. (2004). The haemocytometer was wrapped with a
damp filter paper in an airtight petridish for an hour to make the calibrations
conspicuous and enhance counting of individual sperm cells. The
86
haemocytometer was wiped dry with tissue paper before use. 5ml of 0.9%
physiological saline was measured into a clean test tube with a 10ml pipette.
0.01ml of raw semen was aspirated into a tuberculin syringe and dropped into
the test tube containing 5ml physiological saline. Five drops of absolute ethyl
alcohol was piptted and transferred into the mixture and thoroughly mixed. The
test tube containing the mixture was allowed to stand on the bench for an hour
to immobilize the sperm cells. Using a capillary pipette, both chambers of the
haemocytometer were filled with a drop of the diluted semen and allowed to
settle for two minutes. Using a light microscope, the number of spermatozoa in
the five large squares of the haemocytometer was determined at (x400)
magnification. Two counts were taken for each sample and the average
recorded. The number of spermatozoa per sample of semen was calculated
with the formular: 610xDxA
DfxcountedaspermatozoofNumber
Where Df = Dilution factor (0.6)
A = Area of the haemocytometer (1/400mm)
D = Depth of the haemocytometer (0.1mm)2
Total sperm count = sperm concentration x total volume of ejaculate
(Hafez, 1985).
3.8 Experiment 2: Artificial Insemination, Fertility and Hatchability
Experiment 2 was performed using a total of 48 hens, which were
divided into two groups – 1 and 2, corresponding to the management methods
adopted in experiment 1 with 24 hens in each group and six hens per treatment
(ejaculation frequency). Group 1 hens were inseminated with semen pooled
87
from group 1 toms while group 2 hens were inseminated with semen pooled
from group 2 toms. The hens were sexually stimulated by “venting” or
“cracking” as described by Hafez (1984) and modified as described in
www.aviagen.com (2009).
The toms previously evaluated for semen quality indices were selected
based on high score and used as semen donors for the artificial insemination. 2
toms were selected per frequency of ejaculation, making a total of 8 toms per
group as shown in Tables 16 and 17.
Table 16: Insemination of Turkey hens based on frequency of semen
collection and rearing methods
Factor A
(management
systems)
No of toms and
hens
Factor B frequency of
semen collection
X1 X2 X3 X4
intensive Males 8
Females 24
2
6
2
6
2
6
2
6
2
6
Semi-intensive Males 8
Females 24
2
6
2
6
2
6
Where x1 = control; x2: twice week collection; x3: three times week collection;
x4: = Four times week collection
Semen was pooled from the donor males with 10ml beakers and
maintained warm in an improvised incubation kit. All the syringes as well as
the diluents were maintained warm in the incubation kit. An aliquot (0.2ml) of
freshly collected undiluted semen pooled from each male group was drawn
with a syringe and added directly to 2ml warm physiological saline in a 10ml
beaker. The semen and diluent were thoroughly mixed by shaking
gently.0.25ml of the diluted semen containing 20 million spermatozoa was
88
deposited into the vagina of each female within 30 minutes of collection using
a clean, dry plastic syringe. All hens were inseminated 3 times weekly for
three weeks prior to outset of egg production and there after, once weekly
throughout the experimental period of sixteen weeks.
The following precautions were taken during the insemination.
1. The vent of the toms was cleaned with cotton wool damped with
physiological saline before semen collection
2. The hens were gently handled during insemination (each hen was caught
carefully, allowed to stabilize before insemination and dropped gently
thereafter).
3. The exteriorized vent of the hens was not touched to avoid contamination.
4. Disposable insemination syringes were used during insemination (one
syringe/hen).
5. Poor quality/contaminated semen was not used for insemination.
6. The semen was used within 30 minutes of collection.
7. The semen diluent and syringe were kept warm all through each
insemination session.
8. The semen and diluent were thoroughly mixed together.
9. The hens were adequately stimulated by massaging the cloacal area and
0.25ml of semen containing 20 million sperm cells was properly deposited in
the oviduct at a depth of 7cm.
10. Detergent was not used to wash the inseminating instruments
(www.aviagen.com, 2010)
89
Table 17: Pooling of semen from groups and plan for insemination of hens
Factor (A) Frequency of Ejaculation
Factor (B)
Management
System
Groups No. of males and
females
1X 2X 3X 4X
1 Semi- Intensive Males (8) 2 2 2 2
2 Intensive
Females (24)
Males (8)
Females (24)
6
2
6
6
2
6
6
2
6
6
2
6
Where x1= (control); x2 = (twice week collection); x3 = (thrice wee collection);
x4 =(4 times per week)
3.9 Egg Collection, Candling and Hatching
Eggs were collected daily from hens in each treatment group, properly
identified, and stored in an airy environment in egg crates. The eggs were
incubated in a locally fabricated incubator and set for incubation every four
days. The set eggs were candled on the eighteenth day of incubation. After
candling and at the end of incubation period (28 days), eggs that did not hatch
were classified and recorded as follows:
1. Fertile eggs
2. Infertile eggs (egg containing milky white albumen, no embryo, or
brownish albumen )
3. Early dead embryos (embryos without visible formation of eyes)
4. Late dead embryos (embryos with large black eyes, but lacking
feather formation)
5. Hatched eggs
90
All dead embryos were considered fertile. The fertility levels of each
treatment flock was calculated as outlined by Sotirov et al. (2002) and recorded
in percentage determined by
Fertility (%) 1
100x
seteggsofnumber
eggsfertileofnumber
The hatchability levels per treatment was calculated as outline by Hafez (1985)
and Wilson (2008) and recorded in percentage.
Hatchability = 1
100x
candlingateggFertile
hatchedpoultsofNumber
3.10. Statistical Analysis
The data obtained from experiments 1 and 2 respectively were subjected
to analysis of variance based on the 2 x 4 factorial arrangement in a
Completely Randomized Design (CRD) using Statistical Package for Social
Sciences (SPSS) computer package (SPSS, 2001). Significant means were
separated using the Duncan option of SPSS.
91
CHAPTER FOUR
RESULTS AND DISCUSSION
The result of the study on the effects of management conditions and
frequency of ejaculation on semen quality of local toms are presented in Table
18 below
Table 18: Mean ± SE of semen quality traits of toms ejaculated at various
frequencies under intensive and semi- intensive systems of
management
Parameters
Management
System (factor A)
Ejaculation Frequencies ( factor B)
Overall Mean X 1 X 2 X 3 X4
SV (ml)
Intensive
Semi-intensive
Overall
0.22 ± 0.01b
0.26 ± 0.01a
0.24 ± 0.01ns
0.28 ± 0.01a
0.29 ± 0.02a
0.29 ± 0.11ns
0.22 ± 0.02b
0.26 ± 0.02a
0.24 ± 0.01ns
0.21 ± 0.02b
0.19 ± 0.01b
0.20 ± 0.01ns
0.24 ± 0.01**
0.24 ± 0.01*
PM(%) Intensive
Semi-intensive
Overall
87.73 ± 1.31c
90.67 ± 1.07b
89.20 ± 0.87ns
97.92 ± 0.46a
97.03 ± 0.54a
97.47 ± 0.36ns
92.67 ± 0.73b
92.53 ± 0.68b
92.60± 0.49ns
91.89 ± 0.66b
91.65 ± 0.68b
91.77 ± 0.03ns
92.48 ± 0.62**
92.97 ± 0.49**
SC(x109)
Intensive
Semi-intensive
Overall
10.51 ± 0.03a
10.44 ± 0.07a
10.48 ± 0.04ns
10.42 ± 0.07a
10.44 ± 0.07a
10.43 ± 0.05ns
9.24 ± 0.26b
8.77 ± 0.35b
9.00 ± 0.22ns
8.90 ± 0.36b
8.99 ± 0.34b
8.94 ± 0.27ns
9.76 ± 0.15*
9.66 ± 0.16**
LS((%) Intensive
Semi-intensive
Overall
84.13 ± 1.09b
80.33 ± 5.31b
82.23 ± 2.69ns
92.10 ± 6.01ab
97.90 ± 0.66a
91.71 ± 3.02ns
98.47 ± 0.13a
98.27 ± 0.19a
98.37± 0.12ns
98.30 ± 0.18a
98.27 ± 0.18a
98.28 ± 0.13ns
93.25 ± 1.67**
93.69 ± 1.65**
NS(%) Intensive
Semi-intensive
Overall
88.13 ± 1.36b
88.67 ± 1.36b
88.40 ± 0.95ns
98.50 ± 0.15a
98.67 ± 0.15a
98.59 ± 0.11ns
90.30 ± 1.29b
90.53 ± 1.05b
90.42± 0.82ns
88.53 ± 0.77b
89.63 ± 0.86b
89.08 ± 0.55ns
91.37 ± 0.74**
91.88 ± 0.70**
AS(%) Intensive
Semi-intensive
Overall
11.87 ± 1.36a
11.33 ± 1.36a
11.60 ± 0.95ns
1.53 ± 0.16b
1.33 ± 0.15b
1.43 ± 0.11ns
10.37 ± 1.26a
10.47 ± 0.87a
10.42± 0.75ns
11.47 ± 0.77a
10.37 ± 0.86a
10.92 ± 0.55ns
8.81 ± 0.74**
8.38 ± 0.69**
TS(x 109) Intensive
Semi-intensive
Overall
2.98 ± 0.07a
2.68 ± 0.11a
2.83 ± 0.10ns
2.48 ± 0.16b
2.59 ± 0.18a
2.53 ± 0.10ns
2.30 ± 0.12b
2.36 ± 0.12a
2.33 ± 0.08ns
1.68 ± 0.17c
1.69 ± 0.19c
1.69 ± 0.13ns
2.36 ± 0.09**
2.33 ± 0.09**
a, b, c means with different superscripts in rows and columns for different traits are significant (P<0.01)
Key: SV – Semen Volume; PM – Progressive Motility; SC – Sperm Concentration; LS – Live Sperm; DS – Dead
Sperm; NS – Normal Sperm; AS – Abnormal Sperm; TS – Total Sperm in Ejaculate
**: Statistical significant at 0.01 level
*: Statistical significant at 0.05 level
92
Semen Volume
The results shown in Table 20 indicate that frequency of semen
collection significantly (P <0.05) affected semen volume in both intensive and
semi-intensive management groups of toms. It was observed that twice per
week semen collection yielded the highest volume (0.28 + 0.01 ml and 0.29
+0.02ml) in both intensive and semi-intensive management systems
respectively. The management conditions adopted significantly (P < 0.05)
affected semen volume in treatments x1, and x3 with the semi-intensive group
producing significantly (P< 0.05) higher ejaculate volume than intensively
reared groups. Semen volume values of semi-intensive and intensively reared
groups were statistically similar in treatments x2 and x4. Mean values for semen
volume in the two management groups were lower under x4 suggesting that
high frequency of ejaculation (four times per week) caused lower ejaculate
volumes under both management groups. The toms under semi-intensive
rearing produced higher ejaculate volumes in all treatments except for
treatment x4 where ejaculate volume of semi-intensive toms became slightly
lower. The result on effect of frequency of collection on semen volume were in
agreement with those of Noirault and Brillard (1999), and Nwachukwu et al.
(2006) who reported a decrease in semen volume with increasing frequency of
semen collection. The result of this study disagrees with those of Zaharaddeen
et al (2005), who reported lower values for semen volume at once and twice
per week collection frequencies respectively. The lowest ejaculate volumes
(0.21 + 0.02 ml and 0.19 + 0.01 ml) recorded in this study were higher than the
93
mean value (0.17 + 0.02 ml) recorded by Zaharaddeen et al (2005) for local
turkeys in Northern Nigeria. The ejaculate volume obtained at two times per
week collection falls within the normal range (0.25 – 0.35 ml) reported by
Burke (1984), and (0.26 – 0.35 ml) reported by Bakst (1990).
The superiority of toms under semi-intensive system over their intensive
counterparts in semen volume could be attributed to their freedom to forage
which gave them the opportunity to pick various insects and plants from the
range some of which may contain sex stimulating phytochemicals. Sex
stimulating plants such as Withania somnifere (Ashwagandha), Tribulus
terrestris (Gokshura), Mucuna prurieus (Atmagupta) Argyreia speciosa
(Brahaddarak), Anacyclus pyrethrum (Akarkaram) etc. have been reported as
potent plants used to improve fertility, libido, rebuild sexual vitality and to
restore proper and healthy sexual functions in broiler breeders (Durape, 2007).
Upenrda et al. (2000), studied the effect of herbal preparations in male broiler
breeders and observed a significantly higher seminal volume per ejaculate and
semen quality of males from the group supplemented with herbal powder as
compared to the control. The result of this study appears to suggest that
forages picked by toms under semi-intensive management system contained
different beneficial phytochemicals which may have helped in improving
semen volume and viscosity in turkey breeder males reared under this system.
The apparent reasons for the differences between the semen volume
obtained in this study and that reported by Zaharaddeen et al (2005) could be
due to differences in genetic background of the turkeys used and age of the
94
toms. The authors may have used aging toms while in this study young toms
exhibiting tremendous vitality were used which was reflected in the quality of
ejaculates they produced during the study. The result of this study suggests
that more breeding units can be prepared with the large semen volumes
obtained from the toms under both management systems for inseminating more
females in artificial insemination programme.
Progress Motility
Percentage progressive motility was significantly (P < 0.05) affected by
frequency of semen collection in this study. Percentage progressive motility
was highest (97.92 + 0.46% and 97.03 + 0.54%) when semen was collected
twice per week from the toms under intensive and semi-intensive management
systems respectively. The results also showed that within ejaculation
frequencies significantly (P< 0.05) higher motility values were recorded for
toms reared under semi- intensive management than those reared intensively in
treatment X1 while in other treatments X2, X3 and X4 mean motility values
were statistically similar for toms reared under intensive and semi-intensive
systems. The result of this study indicated that toms under semi-intensive
management system produced more viable sperm (90.67 + 1.07%) than the
toms under intensive management (87.73 + 1.31%). Intensively reared toms
under once per week collection frequency yielded the lowest motility value
(87.73 + 1.31%) Also the semi-intensive toms under once per week collection
yielded the lowest motility value compared to other collection frequencies. It
does appear that for both rearing conditions, sperm motility of toms increased
95
as collection frequencies increased with the highest values obtained for twice
per week collection frequency.
However, the motility values recorded in this study were higher than
84.25 + 2.23% and 83.47 + 2.36 % which were the highest values recorded by
Zaharadeen et al. (2005) in local and exotic turkeys respectively. Holsberger et
al. (1998) reported a mean motility value of 90.8 + 1.3% for high mobility
phenotype exotic turkeys. Noirault and Brillard (1999) reported mean motility
value of 89.69 + 0.33% for British United Turkeys. The values obtained in this
study under the two management systems were slightly higher than these
reported by these authors. This may be due more to age of toms used than to
genetic differences. The toms used in the present study were pubertal toms
exhibiting considerable vigour and vitality. They were apparently younger than
toms used by Zaharadeen et al. (2005) and Noirault and Brillard (1999).
Bearden et al. (2004) reported that age of toms may affect sperm motility of
ejaculates in turkeys.
Although the result of this study is not in agreement with those of
Zaharaddeen et al (2005) who reported no significant effect of ejaculation
frequency on sperm motility, it is in consonance with those of Noirault and
Brillard (1999) who reported lower percentage progressive motility values
following a rest period when toms were ejaculated at closer ejaculation
frequencies.
96
Sperm Concentration
Sperm concentration was significantly (P < 0.05) affected by frequency
of semen collection under both intensive and semi-intensive rearing conditions.
The result also indicated that sperm concentration was statistically the same
when semen was collected once and twice per week in both management
systems. These results appeared to show that sperm concentration was higher at
once and twice per week semen collections and decreased significantly (P <
0.05) at three times and four times per week collection frequencies under the
two management systems. Earlier research reports showed that when semen
was collected daily for three days the first few ejaculates will contain more
sperm than subsequent ejaculates. This is because the number of sperm within
the cauda epididymides is reduced by ejaculation until it stabilizes at about
25% (Amann, 1970). It was also discovered that once such stabilization has
occurred, the number of sperm obtained in subsequent ejaculates should
oscillate around a mean value characteristic of that male at that time of the year
(Amann, 1970).
The sperm concentration values obtained in this study were however in
agreement with those of Cecil et al. (1988), Zaharaddeen et al (2005)
Nwachukwu et al. (2006) who had earlier reported that sperm concentration
decreases with increasing frequency of semen collection. Although semen
volume was not significantly (P < 0.05) affected when semen was collected up
to three times per week from toms under semi- intensive management, sperm
concentration became affected beyond twice per week collection frequency. It
97
therefore appears that if semen is collected once and twice per week, local toms
will give maximum sperm output. It has been reported that varying the
frequency of semen collection not only impairs the number of spermatozoa
available for insemination, but also alters the overall reproductive performance
in breeder flock (Noirault and Brillard, 1999). In this study, high sperm
concentration recorded in both management systems appears to suggest that
high fertility could be achieved with the toms when used in artificial
insemination programmes. This is because ejaculates with low sperm
concentration have been associated with low fertility (Bearden et al., 2004).
Live Sperm
The result of this study indicated that ejaculation frequency significantly
(P < 0.05) affected the percentage live sperm produced by toms under the two
rearing conditions. It was observed that percentage live sperm decreased 84.13
+ 1.09% and 80.33 + 5.31% when semen was collected once per week in both
intensive and semi-intensive management systems respectively. It was also
observed that the percentage live sperm increased with increase in frequency of
semen collection in both management systems. Percentage live sperm did not
differ (P> 0.05) between management systems when semen was collected
twice, three times and four times per week. These results were not in agreement
with those of Santayana (1985) and Zaharaddeen et al. (2005) who reported
that ejaculation frequency did not affect any other semen quality trait in toms
apart from sperm concentration. The results of this study were consistent with
those of Donoghne et al. (1995), and Noirault and Brillard (1999) who
98
observed persistent, but moderate increase in percentage viable spermatozoa
from males collected more frequently. Zaharaddeen et al. (2005) reported
percentage live sperm to be 83.17 + 1.99% and 83.75 + 1.41% for exotic and
local turkeys respectively. The values obtained for percentage live sperm in
this study were slightly higher than those reported by Zaharaddeen et al.
(2005), possibly due to differences in climatic variables between the Sudan
savanna region of Northern Nigeria where the authors carried out their studies
and the humid tropical climate where the present study was done. Variations in
components of climatic environment such as solar radiation, air temperature
and relative humidity could cause visible changes in reproductive performance
of males leading to changes in ejaculate characteristics (Egbunike and
Jeyakumar, 1980). The mean percentage live spermatozoa recorded in this
study for the toms under both systems of management was high, exceeding the
75% minimum base line value reported by Hafez, (1985). This result however
appears to show that higher fertility could be achieved with active use of local
toms of the humid tropics in planned breeding programme. This is likely so,
since Donoghue and Waker (1985), reported that high correlation exists
between sperm viability and fertility.
Normal Sperm
The result of this study indicated that frequency of semen collection
significantly (P < 0.05) affected the percentage normal spermatozoa in both
intensively and semi-intensively reared toms. Higher percentage of normal
spermatozoa 98.50 + 0.15% and 98.67 + 1.36% were recorded respectively
99
when semen was collected twice per week in intensive and semi-intensive
management systems compared to other ejaculation frequencies where lower
values were recorded. No significant differences (P < 0.05) were observed
between management systems in Normal sperm at all ejaculation frequencies.
It was observed that mean values for percentage normal sperm were
significantly (P < 0.05) lower in both systems of rearing when semen was
collected once 8813 + 1.36% and 88.67 + 1.36%, three times 90.30 + 1.29%
and 90.53 + 1.05%, and four times 88.53 + 0.77% and 89.63 + 0.86% per
week. The results obtained for normal sperm were not in agreement with those
of Zaharaddeen et al. (2005) who reported no significant difference in
percentage normal sperm when local toms were ejaculated at various
frequencies. The percentage morphologically intact sperm recorded in this
study; irrespective of ejaculation frequency and management system were
consistent with the acceptable rage (80% - 100%) reported by Hafez (1985) and
Bearden et al (2004).It therefore appears that the variation in frequencies of
ejaculation and rearing conditions adopted in the present study did not
adversely affect the sperm production and storage mechanisms of the local
toms. This is because, Anderson (2001), reported that partial or complete
degeneration of the sperm tubules may result to high production of abnormal
spermatozoa thereby reducing the proportion of normal spermatozoa. The
result therefore indicates that high fertility could be achieved with the local
toms in artificial insemination programme under the ejaculation frequencies
and management methods adopted.
100
Abnormal Sperm
The result of this study indicated that frequency of semen collection
significantly (P < 0.05) affected the percentage abnormal sperm under the two
rearing conditions. Significantly (P < 0.05) lower mean values (1.53 + 0.16%
and 1.33 + 0.15%) were respectively recorded for abnormal sperm when semen
was collected twice per week in both intensive and semi-intensive management
systems. There were no significant (P > 0.05) effects of management system on
percentage abnormal sperm at all the frequencies of ejaculation adopted.
Significantly (P < 0.05) higher mean values were obtained for percentage
abnormal sperm in both management systems when semen was collected once
per week (11.87 + 1.36% and 11.33 + 1.36%), three times per week (10.37 +
1.26% and 10.47 + 0.87%), and four times per week (11.47 + 0.77% and 10.37
+ 0.86%) The values obtained for abnormal sperm in this study were consistent
with those of Sotirov et al. (2002), and Zaharaddeen et al. (2005). Sotizov et al.
(2002) fed 14% and 17% crude protein diets to White Imperial Breed of
turkeys and reported percentage abnormal spermatozoa to be 10.03% and
10.621% for 14% and 17% crude protein diets respectively. Zaharaddeen et al.
(2005) subjected White Nicholas toms and local toms to three frequencies of
semen collection per week and reported percentage abnormal sperm to be 11.50
+ 1.56% and 14.33 + 1.56% for once per week, 11.42 + 1.10% and 12.58 +
1.10% for twice per week, and 10.67 + 1.10% and 13.92 + 1.10% for three
times per week for white Nicholas and Local toms respectively. These results
were compared favourabley with the result obtained in this study except for
101
their results in toms ejaculated twice per week which were considerably lower
in the present study. The values for percentage abnormal sperm recorded in
this study were below the 20% reported by Hafez (1985) and Bearden et al.
(2004) as base line value beyond which fertility may be impaired.
The resent results, however, indicate that high fertility could be achieved
with local toms under various frequencies of ejaculation and rearing systems.
This is because, morphological sperm defects generally affect fertility more
than low sperm motility (Lukaszewicz, 2003). Thatohatsi (2009) observed that
an increase in percentage abnormal sperm impairs fertility of breeder flock.
The most frequent sperm abnormality observed in this study was mid-piece, tail
and sperm head deformities. However, the reason for the higher values
obtained for once per week semen collection frequency may be due in part to
aging of spermatozoa resulting in loss of membrane integrity following
peroxidation in the vas deferens (Noirault and Brillard, 1995). In this study,
sperm head and mid-piece defects were higher than other abnormalities.
Similar results have been reported in the cock by Alkan et al. (2001) who
attributed it to the relatively long and slender mid-piece of chicken sperm cells
which makes it more vulnerable to damage during slide preparation. It has been
reported that the acrosome and mid-piece are the most sensitive regions in
chicken sperm, with the mid piece being quicker to deteriorate than other
regions when exposed to adverse factors (Alkan et al., 2001).
102
Total Sperm in Ejaculate
Total sperm in ejaculate was significantly (P < 0.05) affected by
frequency of semen collection under both rearing systems in both groups of
toms. It was observed that once per week semen collection yielded the highest
total sperm in ejaculate under the two rearing systems 2.98 + 0.12 x 109 and
2.34 + 0.12 x 109 respectively. The results also indicated that ejaculating toms
four times per week resulted in the least values for total sperm in ejaculate
(1.68 + 0.17 x 109 and 1.69 + 0.19 x 10
9) in both intensive and semi-intensive
management systems respectively. There were no significant (P < 0.05) effects
of management system on total sperm in ejaculate at once and four times per
week ejaculation frequencies. Rearing system significantly (P < 0.05) affected
total sperm at two times and three times per week collection frequencies. The
results of this study were in agreement with those of Santayana (1985) who
reported a progressive decline in total sperm with increased ejaculation
frequency. Nwachukwu et al. (2006) also reported significant influence of
ejaculation frequency on total sperm in the cock. The values for total sperm
obtain in this study were lower than those reported by Korlowska et al. (2005)
for exotic toms. This author reported 4.16 + 0.38 x 109, 3.10 + 0.58 and 3.02 +
0.49 x 109 for BIG -6, Hybrid Large White and White Nicholas toms
respectively. Zaharaddeen et al. (2005) ejaculated local toms three times per
week and reported 101. 52 ± 20.41 x 109 and 47.04 ± 23.15 x 10
9 , 129.43 ±
16.37 x 109 and 43.92 ± 16.37 x 10
9, 62.22 ±13.37 x 10
9 and61.47 ± 13.37 for
once twice and three times per week semen collections respectively. It was
103
observed that values for total sperm were statistically the same when semen
was collected once, (2.83 + 0.10 x 109), twice, (2.53 + 0.08 x 10
9) and three
times 2.36 ± 0.12 x 109
from the toms under semi-intensive management. This
result is in agreement with those of Zaharaddeen et al. (2005) who found no
significant differences in total sperm in ejaculate at once, twice and three times
per week semen collection frequencies. The result of this study also indicated
that management system had significant effect on total sperm, with semi-
intensive management system producing higher values for total sperm at twice
(2.59 + 0.18 x 109) and three times (2.36 + 0.12 x 10
9) per week semen
collections frequencies.
The reason for higher values of total sperm recorded in this study for the
toms under semi-intensive management system could be attributed to the
beneficial effect of phytochemicals on gametogenic and androgenic functions
of the tastes and seminiferous tubules (Durape, 2007). Also, differences in
total sperm in ejaculate within and between treatment groups could be
attributed to individual variability in sperm production rate (Thatohatsi, 2009).
The differences between the result obtained in this study and the reports of
other researchers may be due to variations in genetic lines of the turkeys used
in the experiments (Hafez, 1985; Thatohatsi, 2009). Earlier research reports
indicated that the avian reproductive system is sensitive to the bird‟s
environment. Under poor management and harsh environmental conditions,
the testes dwindle in size and exhibit reduced sperm production capabilities
(Durape, 2009). The results obtained in this study indicate that high numbers of
104
breeding unit and high fertility could be achieved with local toms when used in
artificial insemination since Thatohatsi (2009) reported a positive correlation
between total sperm inseminated and fertility. This is because even though it
takes one single sperm to fertilize an egg, adequate number of spermatozoa
must be available at the site of fertilization to ensure high fertility and
hatchability (Durape, 2007).The result of this study appears to show that
harvesting semen four times per week in local toms may not produce good
results in local turkeys under artificial insemination programme..
The effects of interaction between ejaculation frequency and
management system on semen quality traits is presented in Table 19
Table 19: Effect of Interaction between Management Systems and
Ejaculation Frequencies (MS x EF) on Semen Quality
Parameters in Local Male Turkeys
Parameters Management
Systems
Ejaculation Frequencies S.E.M Significance
X1 X2 X3 X4
SV 1 0.22 0.28 0.22 0.21
0.01
0.11 2 0.26 0.29 0.26 0.19
PM 1 87.73 97.92 92.67 91.89
0.81
0.07 2 90.67 97.03 92.53 91.65
SC 1 10.51 10.42 9.24 8.90
0.24
0.68 2 10.44 10.44 8.77 8.99
LS 1 84.13 92.10 98.47 98.30
3.58
0.36 2 80.33 97.90 98.27 98.27
DS 1 15.80 1.90 1.53 1.73
0.62
0.80 2 14.87 1.43 1.73 1.73
NS 1 88.13 98.50 90.30 88.53
0.99
0.95 2 88.67 98.67 90.53 89.63
AS 1 11.87 1.53 10.37 11.47
0.97
0.92 2 11.33 1.33 10.47 10.37
TS 1 2.48 2.98 2.30 1.68
0.13
0.90 2 2.68 2.59 2.36 1.69
Key: SV – Semen Volume; PM – Progressive Motility; SC – Sperm
Concentration; LS – Live Sperm; DS – Dead Sperm; NS – Normal Sperm; AS
– Abnormal Sperm; TS – Total Sperm in Ejaculate
1: Intensive System
2: Semi-intensive System
105
Table 20 shows the interaction effects between management systems and
frequency of semen collection on semen quality parameters. The analysis did
not detect any significant interaction effects (P > 0.05) of management systems
x ejaculation frequency (MS x EF) on any of the seminal characteristics. The
result however, suggest that both management systems could be adopted by
farmers for raising high performing breeder toms for enhanced semen quality
and quantity leading to significant improvement in fertility and hatchability of
artificially inseminated hens.
Fertility and Hatchability
The result on the effects of management conditions and frequency of
ejaculation on fertility and egg hatchability in local turkeys are presented in
Table 20 below
Table 20: Mean ± SE of fertility and hatchability traits of local turkeys by artificial insemination under
intensive and semi- intensive systems of management
Parameters
Management
System
Ejaculation Frequencies
Overall
Mean X 1 X 2 X 3 X4
NF
Intensive
Semi-intensive
Overall
9.25 ±1.36b
11.25 ± 1.25a
10.25 ± 0.93ns
10.13 ± 0.95a
11.13 ± 1.20a
10.63 ± 0.75 ns
7.38 ± 0.82b
9.88 ± 1.19a
8.63 ±0.77 ns
7.75 ± 0.10b
8.13 ± 1.16a
7.94 ±0.74 ns
8.63 ± 0.54 ns
10.09 ± 0.61ns
NI
Intensive
Semi-intensive
Overall
2.50 ± 0.71a
1.50 ± 0.46b
2.00 ± 0.34ns
1.00 ± 0.42a
0.88 ± 0.30a
1.06 ± 0.25ns
2.50 ± 0.54a
2.13 ±0.52a
2.31± 0.36ns
3.13 ± 0.30
2.38 ±0.46
2.75 ± 0.42ns
2.25 ± 0.28ns
1.75 ± 0.24 ns
NDE Intensive
Semi-intensive
Overall
1.13 ±0.40a
1.50 ± 0.38a
1.31 ± 0.27ns
0.00 ± 0.00b
0.13 ± 0.13b
0.06 ± 0.06ns
0.00 ± 0.00b
0.25 ± 0.25a
0.13 ± 0.13ns
0.50 ± 0.38ab
0.00 ± 0.00a
0.25 ± 0.20ns
0.41 ± 0.16**
0.47 ± 0.16**
NLE Intensive
Semi-intensive
Overall
0.00 ± 0.00
0.00 ± 0.00
0.00 ± 0.00ns
0.00 ± 0.00
0.00 ± 0.00
0.00 ± 0.00ns
0.13 ± 0.13c
0.00 ± 0.00b
0.06± 0.06ns
0.00 ± 0.00
0.00 ± 0.00
0.00 ± 0.00ns
0.03 ± 0.03ns
0.00 ± 0.00ns
NHE Intensive
Semi-intensive
Overall
8.13 ± 0.19b
9.75 ± 1.35c
8.94 ± 0.92ns
10.13 ± 0.95b
11.00 ± 1.15a
10.56 ± 0.74ns
7.25 ± 0.86b
9.63 ± 1.27a
8.44± 0.80ns
7.25 ± 0.98
8.13 ± 1.16
7.69 ± 0.74ns
8.19 ± 0.52ns
9.63 ± 0.61ns
PF Intensive
Semi-intensive
Overall
80.90 ± 4.58b
84.39 ± 4.63ab
83.65 ± 3.16ns
90.42 ± 4.10a
92.18 ± 2.79a
90.05 ± 2.41ns
78.22 ± 5.20b
80.18 ± 4.59a
79.20± 3.36ns
71.59 ± 4.75b
76.01 ± 2.65a
73.80 ± 2.72ns
82.53 ± 2.43ns
81.44 ± 2.25**
PH Intensive
Semi-intensive
Overall
89.30 ± 3.68b
96.88 ± 3.13a
93.09 ± 0.13ns
100.00 ± 0.00a
100.00 ± 0.00a
100.00 ± .00ns
97.91 ± 2.09ab
99.16 ± 0.84a
98.54± 0.07ns
94.16 ± 4.02ab
85.11 ± 4.20a
89.64 ± 0.09ns
95.34 ± 1.57ns
95.29 ± 1.66ns
a, b, c means with different superscripts in rows and columns are significantly (P<0.05) different
means without superscripts in rows and columns are not significant (P>0.05)
Key:
NF – Number of Fertile Eggs; NI – Number of Infertile Eggs; NDE – Number of Dead-in-Shell Embryo; NLE – Number of Late Dead Embryo;
NHE – Number of Hatched Eggs; PF – percentage Fertility; PH – percentage Hatchability
**: Statistical significant at 0.01 level
*: Statistical significant at 0.05 level
106
Number of Fertile Eggs (NF)
The number of fertile eggs (NF) were significantly (P < 0.05) affected in
hens inseminated with ejaculates collected under different frequencies. The
highest fertility results were obtained for hens inseminated with once per week
and twice per week ejaculates than those inseminated with semen from other
frequencies in both intensively and semi-intensively reared toms. Fertility
values appear to be generally better in hens inseminated with semen of toms
reared under semi-intensive condition. Between treatments means were
however higher in hens inseminated with semen of toms under semi-intensive
management. The differences in fertility result obtained in this study could be
attributed to the beneficial effect of fertility enhancing phytochemicals
consumed by the toms under semi-intensive management in the range. This is
in agreement with the report of Durape (2007), who used phytochemical
rejuvenators to increase fertility from 95.1% to 97.3% in broiler breeder flock.
Similarly, Narahari (2003), reported that herbal formulations improved fertility
in male broiler breeders. Upenrda et al. (2003) reported improved fertility and
hatchability of eggs laid in hens fertilized with semen of broiler breeder males
given herbal supplementation. Although acceptable fertility level was achieved
in this study, it appears that supplementing formulated breeder diet with grass
and legume forages could increase the fertility potentials of toms even under
intensive management system.
107
Number of Infertile Eggs (NI).
The results indicate significant (P < 0.05) effect of semen obtained
under different ejaculation frequencies on number of infertile eggs
(NI).Between ejaculation frequencies, the number of infertile eggs were
significantly highest (3.13 ± 0.30 and 2.38 ±2.38 ± 0.46) in hens inseminated
with ejaculates obtained at four times ejaculation frequency followed by those
inseminated with semen obtained at three times ejaculation frequency under
both system of rearing. It does appear that even though the insemination doses
adopted (0.05ml) were similar for all treatments they did not contain the same
number of spermatozoa more so as ejaculation frequency significantly effected
total sperm numbers in x3 and x4. Even though lower numbers of infertile eggs
were recorded in the hens inseminated with semen of toms under semi-
intensive management, the number of infertile eggs recorded in this study was
generally within the range (52.9% - 83.4%) reported by Donoghue (2007) for
exotic turkeys. This could be attributed to the good quality semen used in
inseminating the hens as well as the young reproductive age of the hens (Keith,
2008). However, the cause of the higher number of infertile eggs in x3 and x4
may be due to differential physiologic conditions of the semen storage
compartment of hens and may also be due to variations in the condition of the
oviductal environment at the time of insemination which tend to vary from hen
to hen. It has also been reported that the reproductive physiology of the hen at
the time of insemination as well as the development of immunity against sperm
by some breeder hens can lead to infertility (Keith, 2008). Similarly, infertility
108
syndrome – an occasional unexplained infertility in breeder flock has been
reported (Singh, 1964), and may be implicated for the cause of infertile eggs
recorded under some treatments in this study.
Number of Early Dead-Embryo
The result of this study indicated significant (P < 0.05) effects of
ejaculation frequency on the number of early dead embryos (NDE) produced
by the hens under both management systems. It was observed that hens
inseminated with semen collected once per week had the highest number of
early dead embryos 1.50 ± 0.38 and 1.13 ± 0.40 for both intensive and semi-
intensive management systems respectively. The number of early dead embryo
was statistically the same in both managements groups when the hens were
inseminated with semen harvested twice 0.13 ±0.13, 0.00 ± 0.00. At three times
per week 0.25 ± 0.25, 0.00 ± 0.00 and four times per week 0.50 ± 0.38, 0.00 ±
0.00) significant (P <0.05) difference occurred between intensive and semi-
intensive managed groups. The reason for the result obtained for once per week
semen collection could be attributed to the existence of higher number of non-
viable and morphologically abnormal sperm in ejaculates inseminated. Noirault
and Brillard (1999) reported that aging of spermatozoa causes loss of
membrane integrity due to peroxidation. The result of this study appears to
suggest that inseminating hens with semen containing more non-viable and
abnormal sperm could lead to poor fertility and eventual embryo death during
incubation. This is consistent with the findings of Keith (2008) that even
though it takes a single sperm to fertilize an egg, adequate number of
109
morphologically intact sperm is needed to ensure hatchability. Durape (2007)
reported an increase in early embryonic mortality in broiler breeders when few
sperm were available to fertilize an egg. This may be because several factors
including dwindling intra-oviductal sperm motility and oviductal discrepancies
may reduce the number of sperm ascending to the infundibulum which is the
site of fertilization in avians. Thus, the total number of sperm present in the
oviduct is an important factor influencing fertility and early embryonic
mortality in poultry (Devegowda,2009). Eslick and McDaniel (1992) reported
that when inseminating breeders with increasing sperm concentrations, the
number of viable sperm present in the oviduct has considerable influence on
fertility and hatchability. The authors noted that reduced fertility and early
embryonic death will increase with decreased number of viable total sperm
inseminated. Although the hens in both management groups were inseminated
with adequate total sperm, inherent unknown physiological factors of the hens
that may affect the release of adequate number of viable sperm from the sperm
storage tubules could be responsible for the early embryonic mortality recorded
in this study. Although embryo death is common in avian species (Thatohatsi,
2009), early embryonic mortality may be as a result of low sperm activity in
individual hen (Bramwell, 2002). Egg hatchability and embryonic mortality
can further be affected by such factors as poor egg storage, egg size, age of
breeders and incubator shortcomings (Dzoma, 2010). Research reports have
indicated that if hatching eggs are stored for more than one week after lay;
there is increased occurrence of early embryonic mortality and abnormality due
110
to reduction in egg white viscosity and degradation of albumen (Petek and
Dicman, 2006). However, because young hens and toms were used in this
study, and eggs stored within the recommended range (4 days of lay), the cause
of early embryonic death generally recorded in this study appears to be more
associated with incubator shortcomings. Unidentified farm cracks have been
found to cause early embryonic mortality of fertile eggs (Obioha 1992). This
may also be a contributory factor to the cause of early embryonic death
recorded in this study. The result of this study, however, suggests that the
number of early embryonic death could be reduced in an artificial insemination
programme by inseminating hens with semen collected twice or three times per
week.
Number of Late Dead Embryo
The result of this study indicated no significant (P > 0.05) effect of
ejaculation frequency and management system on the number of late dead
embryo. Late embryo death was almost absent in this study.
Number of Hatched Eggs
The result of this study showed no significant (P > 0.05) effects of
ejaculation frequency on the number of hatched eggs recorded when the hens
were inseminated with semen from toms reared under intensive management
system. The number of hatched eggs were also statistically the same when the
hens were inseminated with semen harvested once 9.75 ± 1.35, twice 11.00 ±
1.15, and three times 9.63 ± 1.27 per week from the toms under semi-intensive
management. However, between treatment means showed slightly higher
111
hatchability levels for hens inseminated with semen from the semi-intensive
group of toms across the four ejaculation frequencies. The reason could be
attributed to the intake of plants by the toms under semi-intensive management
in the runs which may contain phytochemicals that may facilitate embryo
viability. This result is in agreement with that of Durape (2007) who recorded
increases in hatchability from 57.2% to 59.1% in broiler breeder hens
following insemination with semen of males fed polyherbal supplementation.
Percentage Fertility and Hatchability
Percentage fertility values were statistically different (P < 0.05) in hens
inseminated with semen ejaculated at various frequencies and followed the
trend recorded for Number of Early Dead Embryo. however better valued were
obtained for hens inseminated with semen ejaculated at two times per week
frequency. In the semi-intensive group, significant differences (P< 0.05)
occurred in percent fertility among hens inseminated with ejaculates collected
at different frequencies with higher values recorded for hens inseminated with
ejaculates collected twice per week (92 .18 ± 2.79%) followed by those
inseminated with semen collected once per day ( 82.39 ± 4.63%) and three
times per week (80.18 ±4.59%). Lowest percent fertility value in semi-
intensive groups was recorded for hens inseminated with ejaculates collected
three times per week (71.01 ±2.65%). Between rearing condition comparisons
within ejaculation frequency showed significant (P < 0.05) differences between
rearing conditions only at once three times per week and four times per weak
112
frequency respectively with higher values recorded for semi-intensively reared
toms at all frequencies of ejaculation.
It seems evident that management system had profound effect on
fertility. The values obtained for fertility were comparable with those of
Kotlowska et al. (2005) who reported average percentage fertility values of
94.51%, 89.89% and 87.5% for Hybrid Large White Nicholas, Nicholas (N –
700) and Big – 6, strain turkeys respectively under intensive management.
Similarly, percentage hatchability recorded in this study were
significantly (P < 0.05) affected by frequency of semen collection and
management system. Percentage hatchability values, ranging from (85.11 ±
4.20% to 100.00 ± 0.00%) recorded in this study were close to the range (95%
to 100%) reported by Keith (2008) in exotic turkeys. Thus, the result of this
study appears to indicate that acceptable fertility and hatchability could be
achieved in local turkeys using artificial insemination. The results of this study
have shown that hatchability of eggs was best in hens inseminated with
ejaculates collected twice per week (100.0 ± 0.00 and 100.00 ± 0.00%)
followed by hens under three times per week ejaculation frequency (97.91 ±
2.09% and 99.16 ± 0.84%) in intensive and semi-intensive groups
respectively. Hens inseminated with semen of toms under semi-intensive
management had significant (P < 0.05) edge over hens under intensively
managed toms in treatments X1 and X3. Judging by these results it may be said
that semi-intensive toms produced better fertility and hatchability results than
the intensively reared toms. In all, twice per week ejaculation frequency
113
produced the best fertility and hatchability results in both intensively reared
and semi-intensive groups. The results on interaction effects of ejaculation
frequency and rearing condition on fertility and hatchability of local turkeys are
presented in Table 21.
Table 21: Effect of Interaction between Management Systems and
Ejaculation Frequency on Fertility and Hatchability Parameters of Local
Turkeys
Parameters Managemen
t Systems
Ejaculation Frequencies S.E.
M
Significanc
e X1 X2 X3 X4
NF 1 9.25 10.13 7.38 7.75
1.13
0.78 2 11.25 11.13 9.88 8.13
NI 1 1.50 1.00 2.13 2.38
0.48
0.80 2 2.50 0.88 2.50 3.13
EMD 1 1.13 0.00 0.00 0.50
0.26
0.33 2 1.50 0.13 0.25 0.00
LMD 1 0.00 0.00 0.13 0.00
0.04
0.40 2 0.00 0.00 0.00 0.00
NHE 1 8.13 10.13 7.25 7.25
1.12
0.89 2 9.75 11.00 9.63 8.13
PF 1 84.90 90.42 78.22 76.59
4.26
0.84 2 82.39 92.18 80.18 71.01
PH 1 89.30 100.00 97.91 94.16
2.79
0.34 2 96.88 100.00 99.16 85.11
Key:
NF – Number of Fertile Eggs; NI – Number of Infertile Eggs; EMD – Early
Dead Embryo -in-Shell Embryo; LMD – Late Dead Embryo; NHE – Number
of Hatched Eggs; PF – percentage Fertility; PH – percentage Hatchability
The present study did not record any significant interaction (P > 0.05)
effect between ejaculation frequency and management system on fertility and
hatchability parameters in both groups. This suggests that any of the
management systems could be adopted to produce the same fertility and
hatchability results in breeder flock of local Nigerian turkeys.
114
CHAPTER FIVE
CONCLUSION AND RECOMMENDATIONS
CONCLUSION
This study was carried out to determine the effect of ejaculation
frequency and management conditions on semen quality, fertility and
hatchability of local turkeys in the humid tropics. The results have shown that
ejaculation frequency significantly affected all semen quality parameters
measured in both intensive and semi-intensive management systems. Twice per
week semen collection yielded the highest mean values for ejaculate volume as
compared to other ejaculation frequencies in both intensive and semi-intensive
management systems. Toms under semi-intensive management system yielded
the highest ejaculate volume in all the treatments. Twice per week semen
collection yielded higher mean values for motility and normal sperm in
ejaculate in both management systems. Percentage viable sperm progressively
increased with increase in ejaculation frequency in both management systems
as shown from sperm motility and proportion of live sperm. The mean values
for sperm concentration were highest for once and twice per week ejaculation
frequencies, and decreased significantly (P<0.05) at three times and four times
per week collection frequencies in both management systems. Significantly
lower mean values were recorded for abnormal sperm at twice per week semen
collection in both management systems. Higher values were recorded at four
times per week collection frequency. The mean values for total sperm in
ejaculate were highest at once per week ejaculation frequency in both
management systems. Total sperm in ejaculate decreased with increasing
115
frequency of semen collection in both management systems with two times per
week collection frequency having higher values than other treatments.
Fertility and hatchability results indicated significant (P<0.05) effect of
ejaculation frequency on all the parameters measured in both management
systems. The highest fertility results were obtained for hens inseminated with
semen pooled from toms ejaculated once and twice per week in both intensive
and semi-intensive management systems. Fertility values appeared to be
generally better in hens inseminated with semen of toms under semi-intensive
management system. The mean values for the number of infertile eggs were
higher in hens inseminated with semen harvested four times per week in both
management systems. The results of this study indicated that hatchability of
eggs was best in hens inseminated with semen harvested twice per week in
both management systems. The hens inseminated with semen of toms under
semi-intensive management system had better hatchability results than those
inseminated with semen of toms under intensive management. Considering the
high fertility and hatchability results obtained in this experiment, there is
evidence of high successes in adopting artificial insemination as a breeding tool
for local turkey production in Nigeria. The study has successfully established
that under both intensive and semi-intensive management systems, adopting
twice and three times per week ejaculation frequencies for local toms reared in
the humid tropics will give satisfactory fertility and hatchability results using
artificial insemination technique. Further studies are therefore required to
develop useful semen preservation/dilution techniques to facilitate effective use
116
of the results of this study in boosting turkey production in rural communities
where it is reared either intensively or semi-intensively.
Recommendations
Based on the results of this study, it is
recommended that:
1. In turkey artificial insemination programmes, local turkeys should not
be ejaculated beyond three times per week for optimum semen quality.
2. Local turkey toms under intensive management system should be
supplemented with or allowed access to fresh forages to improve semen
quality, fertility and hatchability.
3. Artificial insemination could successfully be employed in local turkeys
to obtain high fertility and hatchability results by pooling good quality
semen collected at most three times per week.
4. Farmers can adopt either intensive or semi-intensive management
option for local turkey production in the humid tropics
5. Twice per week ejaculation frequency should be adopted for optimum
semen quality and fertility in artificial insemination programme with the
local tropical turkeys.
117
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