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UNIVERSITY FOR DEVELOPMENT STUDIES TAMALE

EFFECT OF NON-GENETIC FACTORS ON GROWTH TRAITS OF WEST AFRICAN DWARF KIDS AT THE KINTAMPO GOAT BREEDING

STATION

BY: KWARAH WILBERFORCE

(AGT/0607/01)

A DISSERTATION SUBMITTED TO THE DEPARTMENT OF ANIMAL SCIENCE, FACULTY OF AGRICULTURE, IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF

BACHELOR OF SCIENCE DEGREE IN (AGRICULTURAL TECHNOLOGY) JULY 2005

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ABSTRACT

Data on West African Dwarf (WAD) goat collected from 1996 to 2003 at the Kintampo

goat breeding station was analyzed. 944 data was analyzed for birth weight, 875 for

weaning weight and pre-weaning growth rate, 787 kids for yearling weight and post-

weaning growth rate. Analysis of data was done using least squares fixed model using

the GLM procedure in SAS. The influence of non-genetic factors on the traits was

examined. These were sex of kid, type of birth, season of kidding, parity of dam and year

of kidding.

The overall means for the traits were 1.28 ± 0.01 kg for birth weight, 4.68 ± 0.06 kg for

weaning weight, 10.94 ± 0.07 kg for yearling weight, 28.38 ± 0.62 g per day for pre-

weaning growth rate and 26.18 ± 0.30 g per day post-weaning growth rate.

Year of birth was significant (P<0.05) for all growth traits. Type of birth was a significant

(P<0.05) source of variation for all the traits except post-weaning growth rate of kids.

Parity of dam was significant (P<0.05) for all the traits except birth weight. Sex of kid

was significant (P<0.05) for birth weight and yearling weight. Season of birth was not

significant (P>0.05) for all the traits. The weaning weight, yearling weight, pre-weaning

and post-weaning growth rates of kids in the dry season was better than those born in

the wet season except for birth weight which was vice versa. Single born kids grew

faster before and after weaning and also had heavier body weight than twin born kids.

Kids born to higher parity dams performed better in all the traits than those born to

lower parity dams. Male kids had heavier weights and also grew faster pre-weaning.

However, after weaning, growth of female kids was faster than male kids. It is

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recommended that routine adjustment of the non-genetic factors affecting traits of kids

is done often to help in heritability estimation.

TABLE OF CONTENT

Content Pages

Declaration i

Dedication ii

Acknowledgement iii

Abstract iv

Table of Content v

List of Tables viii

List of Figures ix

Chapter One 1

1.0 Introduction 1

1.1 Livestock Production and Improvement in Ghana 1

1.2 Objectives 3

Chapter Two 4

2.0 Literature Review 4

2.1 Characteristics of the West African Dwarf Goat 4

2.2 Non-Genetic Factors and their Effect on Kid Growth Traits 5

2.2.1 Effects of Season of Kidding on Growth Traits 8

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2.2.2 Effect of Sex of Kid on Growth Traits 9

2.2.3 Effect of Type of Birth on Growth Traits 10

2.2.4 Effect of Parity of Dam on Growth Traits 11

2.2.5 Effect of Year of Kidding on Growth Traits 12

2.2.6 Pre-Weaning and Post-Weaning Growth Rates 12

Chapter Three 14

3.0 Materials and Methods 14

3.1 Location of Study Area 14

3.2 Vegetation 14

3.3 Management of Animals 14

3.4 Housing and Feeding 15

3.5 Data Collection and Analysis 16

Chapter 19

4.0 Results 19

4.1 Kid Body Weight Traits 19

4.2 Birth Weight 20

4.3 Weaning Weight 22

4.4 Yearling Weight 24

4.5 Pre-Weaning Growth Rate 24

4.6 Post-Weaning Growth Rate 26

Chapter Five 29

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5.0 Discussion 29

5.1 Kid Body Weight Traits 29

5.1.1 Birth Weight 29

5.1.2 Weaning Weight 29

5.1.3 Yearling Weight 30

5.1.4 Pre-Weaning Growth Rate of Kids 30

5.1.5 Post-Weaning Growth Rate of Kids 31

5.2 Effect of Sex on Kid Growth Traits 31

5.3 Effect of Type of Birth on Kid Growth Traits 33

5.4 Effect of Season of Kidding on Kid Growth Traits 35

5.5 Effect of Year of Birth on Kid Growth Traits 37

5.6 Effect of Parity of Dam on Kid Growth Traits 40

Chapter Six 43

6.0 Summary, Conclusion and Recommendation 43

6.1 Summary 43

6.2 Conclusion 44

6.3 Recommendation 45

References 46

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CHAPTER ONE

1.0 Introduction

1.1 Livestock Production and Improvement in Ghana

The prospects of the livestock industry look brighter for Ghana, since the country has

significant resources as regards livestock production. In tropical countries including

Ghana, there are still abundant if not excessive rural labour force, significant livestock

populations and vast areas of pasture where it is often difficult, if not impossible to

envisage any enterprises other than livestock rearing (Pagot, 1992).

The role of the livestock sub-sector especially in terms of small ruminant production is

increasingly gaining significance in the Ghanaian economy. Ahunu et al. (1995) have

indicated that this sector is an important feature of Ghana’s agriculture, which is the

main stay of the national economy. Livestock production forms an integral part of the

farming systems of Ghana were the economy is agriculture based. Smallholder farm

families who are found mainly in the rural areas and are known to dominate Ghana’s

agriculture keep livestock. The livestock are kept to serve as a source of protein in the

diet of the family, income, manure, performance of traditional and religious

ceremonies.

Ruminants are important to the smallholder rural farmer (Karbo et al., 1999) and to the

nation at large (CSIR and ISNAR, 1980). Sodiq et al. (2003) have indicated that goats are

kept primarily for meat production, so production traits of interest are the number of

young weaned per breeding female per year and their growth rate.

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Livestock production industries worldwide face considerable conflicting challenges and

pressures. In developed countries the challenge is to remain sustainable and

competitive in the face of declining prices, increasing cost, competition and public

pressures. In developing countries the strong increase in demand for livestock products

must be met in circumstances where infrastructure is often minimal, there are

limitations on inputs and the environment places demand on management and on the

adaptive fitness of the livestock. In both situations, solutions to these problems must be

sustainable and appropriate, yet be technically feasible, cost-effective and publicly

acceptable (bishop and Woolliams, 2004).

Genetic improvement is an integral part of many goat development programmes in the

tropics and undeveloped countries, where breeding policies mostly aim to upgrade local

goats by crossbreeding with, either temperate or tropical exotic breeds; and breeding

based on selection, utilizing the variability within a population to upgrade the

population, is less often in such programmes (Kosum et al., 2004). This is due to

availability of apparently superior stock from elsewhere and due to difficulties in

running field based performance recording.

Kosum et al. (2004) have reported that weight is an important selection objective hence

knowledge of the phenotypic and genetic parameters of growth traits is of utmost

importance. The effect of non-genetic or environmental factors on animal performance

means that using a simple measure of performance alone will not give an accurate guide

to the animals’ genetic merit. It is therefore a pre-requisite that knowledge of

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environmental influences and magnitude of their effects should be known in genetic

improvement recommendations and hence decisions that can enhance productivity.

The Food and Agricultural Organization (FAO) of the United Nations (UN) has been

exploring the Open Nucleus Breeding Scheme (ONBS) as a possibility of improving the

organization of nucleus breeding flocks and herds in developing countries (Smith, 1988).

In Ghana, some measures that have been adopted to help boost livestock production

include genetic improvement in nucleus herds such as the ONBS and the use of larger

and heavier imported strains of livestock from the sub-region and from overseas to

cross the indigenous breeds to improve upon weight gain, and other important

commercial traits (Ahunu et al., 1995). They further reported that genetic

improvements in nucleus herds such as Open Nucleus Scheme could bring about

permanent changes, which can be transmitted with little cost to the whole population

as long as environmental changes are not too drastic and natural selection is not

antagonistic to the changes.

The Kintampo Goat Breeding Station is among one of six Ministry of Food and

Agriculture (MoFA) stations required to carry out the ONBS. The station is mandated to

produce improved breeds of the West African Dwarf (WAD) goat in terms of economic

traits like weight and weight gain. This study therefore seeks to examine the non-

genetic factors affecting the phenotype of the animal which will pave the way for

further genetic parameter estimations especially heritability which is needed for

selection.

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1.2 Main Objective

The main objective of this study is to examine the influence of non-genetic factors on

birth weight, weaning weight, yearling weight, pre-weaning and post-weaning growth

rates of the West African Dwarf goat at the Kintampo goat breeding station.

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CHAPTER TWO

2.0 Literature Review

2.1 Characteristics of the West African Dwarf (WAD) goat

The goat, being a small-sized ruminant, is capable of integrating itself into dissimilar

socio-economic situations prevailing in our country. Most important the goat appears to

have a superior adaptation to the arid tropics because of its ability to conserve water,

travel well, graze selectively and to take willingly a wide variety of vegetations

(Gopalakrishnan and Lal, 1996). Restall (1991) reported that goats in the tropics are

aseasonal. One of the most favourable attributes of goats as meat producing animals is

their high rate of reproduction (Wildeus, 1996; Naude and Hofmeyr, 1981) and this is

determined by the number of progeny delivered in a given period of time (Grayling,

2000).

The West African Dwarf (WAD) goat is sometimes referred to as the humid goat. Humid-

zone goats are small size and about 35 – 50 cm high (Pagot, 1992) and weigh between

18 – 20 kg. The average litter weight of the West African Dwarf goat is 1.8 kg. Their very

short legs give them an extreme characteristic appearance. The head is strong with a

straight profile which is slightly concave, the forehead has bony pegs, the ears are long

and often held horizontally or even erect. The neck is short and broad at the base and

the body is round. The limbs are very short and the sub-sternal space is very small being

20 – 25 cm according to the size of the animal. The breed is characterized by short,

thickset frame, while the colour varies from uniform, multi-coloured black, brown to

white (Okorie, 1977). Okorie (1977) has reported that the West African Dwarf goats are

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found throughout the humid topics, usually in the forest zones of the south, as they

appear to be well adapted to this type of climate. Tuah et al. (1992) have reported that

they are the predominant breeds in Ghana and known to be hardy and trypono-

tolerant. They are seldom hornless and have prominent beard in both the adult male

and female. They have very short up-turned tails. The diminutive size of this goat is not

a handicap but rather an adaptation to the various environmental stresses to which it is

accustomed. The WAD goat is known for its prolificacy (Tuah et al., 1992). Bucks would

normally be more acceptable to the does during the months of August through to

January. During the breeding season, the does would come on heat at regular intervals

of about 21 days if not bred. The gestation period ranges between 148 -154 days

(Okorie, 1977).

2.2 Non-Genetic Factors and their Effects on West African Dwarf goats

The sex of an animal is a feature which influences the performance of many traits and is

regarded as an external influence on them. In addition, the season of kidding has an

effect on the growth traits of kids. Since seasons and months have been shown to affect

significantly the incidence of oestrus, it is conceivable that climatic factors such as the

occurrence of rain, which is associated with herbage growth, may be involved. This is

also suggested by the fact that the total annual rainfall and the percentage of does

kidding or kids born have been shown to significantly correlate (Payne, 1990). The size

of the mother is also important in determining the growth of the foetus and its weight

at birth. However, undernutrition of the mother has little effect on the growth of the

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surviving foetus in the early stages of its development (Robinson, 1977). Maternal

undernutrtion later in pregnancy however can have a profound effect (Pearson, 1992).

Poor nutrition of pregnant ewes especially during the dry season tends to decrease birth

weight while kids born during the rainy season are generally heavier (Eltawil et al.,

1970). Nutrients have to reach the foetus through the placental circulation hence

anything that limits blood supply to the placenta and foetus or interferes with the

growth or function of the placenta would hinder foetal growth. There are several

physiological situations where this may occur. The first is an exceptionally large litter in

species that normally have multiple births (twins and triplets) whereas the most usual

number is one.

The phenotype of an animal is the way the animal looks or performs and is the

combined effects of all genetic and environmental influence. Environmental effect plays

a major role in the growth and development of an animal as well as its performance of

each economically important trait. Within any environment there will almost always be

variation in the expression of traits and therefore the opportunity for producers to make

genetic improvements (Thompson, 2004). Das (1993), Ingo (1999), Awemu et al., 1999,

Bearden and Fuquay, 2000) have all demonstrated that environmental factors exert

significant influence on reproductive performance.

Individuals making up a population of given specie are not identical to each other. This

variation comes from several origins. Golapakrishnan and Lal (1996) have indicated that

on one hand, all the individuals of a population do not live in exactly the same

environmental conditions and thus do not present the same physiological and

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morphogical characteristics. Also, they do not all have the same genetic make-up and

there is a certain variation within the whole population (Gopalakrishnan and Lal, 1996)

hence superimposing of environmental influence which themselves have continuous

variation on characters.

Gopalakrishnan and Lal (1996) also indicated that estimation of the genetic parameters

of populations is still difficult at this stage due to the lack of control of environmental

factors. In most tropical conditions, the animals are totally subject to extremely severe

environment (cyclical food stress, irregular watering, high disease risks, excessive

temperature and humidity etc) which is very variable in time and space. Correction of

these environmental effects such as annual effects, regional effects and herd effects is

very difficult (Pagot, 1992). Moreover, the variance of environmental factors, which is

very high indirectly, reduces the contribution of genetic effects and thus the heritability

of the characteristics (Pagot, 1992). The level of reproductive performance is dependent

on the interaction of genetic and environmental factors and has to be given priority

(Greyling, 2000).

Kosum et al. (2004) have reported that weight is an important selection objectives;

knowledge of the phenotypic and genetic parameters of growth traits is of utmost

importance. It is therefore a pre-requisite that knowledge of environmental influences

and magnitude of their effects should be known in genetic improvement. Application of

such knowledge assists in making appropriate management recommendations and

hence decisions that can enhance productivity.

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The size of offspring at birth is controlled by factors other than nutrition during

pregnancy, the more important of which are sex (Goodwin, 1971; Hassan, 1987 and

Osinowo et al., 1990), breed type (Goodwin , 1971), parity of dam (Hassan, 1987; Ganai

and Pandey, 1990), type of birth (Goodwin, 1971; Adu and Ngere, 1979; Buvanendran et

al., 1987; Osinow et al., 1990,1993) and season of birth (Hassan, 1987; Osinowo et al.,

1992).

The total phenotypic variation (Vp) in performance can be thought of as made up of the

following part: Vp = Vg + Ve + Vge

Where Vp = phenotypic variation (total), Vg = variation due to gene action (genotype),

Ve = variation due to environmental factors, Vge = variation due to interaction or

association of genetic (g) and environmental (e) factors (Weiner, 1994).

The study concentrates on the environmental effect (Ve), which refers to the combined

effect of non-genetic factors on growth traits of an individual. These factors to be

considered include sex of kid, year of kidding, season of kidding, parity of dam and type

of birth.

2.2.1 Effect of Season of Kidding on Growth Traits

Seasonal changes greatly affect the nutrition of all animals. Goats are energetic,

inquisitive and versatile in the art of food gathering and they have a greater tendency

than cattle and sheep to change their diet with changing season (Gopalakrishnan and

Lal, 1996).

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Seasonal influence on a trait such as birth weight has been shown to operate through its

effect on dam’s uterine environment (Eltawil et al., 1970). Poor nutrition of pregnant

does especially during the dry season tend to decrease birth weight while kids born

during the rainy season are generally heavier (Eltawil et al., 1970). Also, the season of

kidding has an effect on the growth traits of kid. Lyatuu et al. (1994) in the arid regions

of Tanzania reported that Blended kids born in the wet season were heavier from birth

to 72 weeks old than were those born in the dry season. Since seasons and months have

been shown to affect significantly the incidence of oestrus, it is conceivable that climatic

factors such as the occurrence of rain, which is associated with herbage growth, may be

involved and that this is also suggested by the fact that the total annual rainfall and the

percentage of does kidding or kids born have been shown to significantly correlate

(Payne, 1990). The effect of seasonal influence on the growth of kids cannot be over-

emphasized.

Akusu et al. (2000) in humid tropics of Ibadan, however, found that the non-significant

effect of season on birth weight would suggest that breeding and kidding of West

African Dwarf goats could be performed all-year-round and that heavier and significant

weaning weights were achieved in kids born in dry season. Adu et al. (1985) also

realized that season of birth had no significant effect on both the birth and weaning

weights of kids.

Das et al. (1996) working at Malya noted that season affected birth weight but was not

significant at weaning. Adu et al. (1985), however, noted that season of birth also had

no significant effect on both the birth and weaning weights of kids.

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2.2.2 Effect of Sex of Kid on Growth Traits

The sex of the animal is a feature, which affects the performance of many traits and is

regarded as an external influence on them (Weiner, 1994). The sex of the kid plays an

important role in the growth rate of the developing kid. Adu et al. (1985) reported that

at birth, male kids were significantly (P<0.05) heavier than female kids. However, that

initial advantage did not persist until weaning, as female kids were significantly (P<0.05)

heavier at this stage. Das et al. (1996) working on Blended goat at Malya reported

significant effect of sex of kid on birth and weaning weight. Males were significantly

heavier and grew faster from weaning onward, implying that sex effects are more

pronounced with age after puberty. These have been attributed to hormonal

differences between sexes and their resultant effects on growth (bell et al., 1970).

Ikeobi and Faleti (1996) also observed that male animals were generally heavier than

female animals. This is expected since weight of male animals is favoured by androgenic

effects (Buvanendran, 1992). Consistent superiority of male kids has been widely

reported (Das and Acharya, 1970; Vesely and Robinson, 1970; Magid et al., 1981;

Fitzhugh and Bradford, 1983; Kiriro, 1986). This has also been attributed to hormonal

differences between sexes and their resultant effects on growth (Velardo, 1958; Bell et

al., 1970; Inyangala et al., 1992). Kosum et al. (2004) also recorded a significant

difference (P<0.01) for sex of kid with respect to birth weight. Das and Sendalo (1991) in

Malya Tanzania reported that sex was significant in improved meat goat. Karua and

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Banda (1992) in Malawi have reported that males and females kids of Saanen goats

were significant in birth weight, weaning weight and weight at one year (364 days).

2.2.3 Effect of Type of Birth on Growth Traits

The most important factor affecting off-take rates is the number of young weaned per

females per year (Bradford, 1993). Twins and triplets are smaller at birth than singles

but their total weight may be more (Goodwin, 1971). Similar observations have also

been reported in Zimbabwe by Tawonezvi and Ward (1987). Akusu et al. (2000) working

on the WAD goat also agree that individual birth weight of kids was negatively

correlated with litter size. Odubote (1992) found that in WAD sheep at Ile-ife, twin and

triplets were heavier than singles and the low birth weight for twin and triplets is offset

by higher litter weight (Bemji et al., 1996). Payne (1990) observed that twinning is

common in goats and there is a good deal of evidence that prolificacy increases with

age. Tuah et al. (1992) working on the WAD goat in Kumasi, Ghana reported that birth

weight was affected (P<0.01) by type of birth. Weaning weight was also affected

(P<0.01) by type of birth, decreasing with increased litter size. Type of birth significantly

affected birth and weaning weight in Blended goats at Malya (Das et al., 1996). Single

born and male kids grew faster than twin born females.

Das and Sendalo (1992) in Malya Tanzania reported that type of birth was significant in

improved meat goat. Males exhibited higher liveweights (P<0.01) than females, whiles

single-born kids were heavier than twins at all ages of weight recording.

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Kosum et al. (2004) found out that type of birth on birth weight was significant (P<0.01).

Adu et al. (1987) however, noted that there were no significant differences between the

weights of single and twin kids both at birth and weaning.

2.2.4 Effect of Parity of Dam on Growth Traits

Sodiq et al. (2003) working on Kacang and Peranakan Etawah goats in Indonesia

reported that parity significantly influenced litter size at birth. Young Does are still

growing and thus must provide for their own growth in addition to the foetal demand

(Inyangala, 1992). The effect of parity of dam on kids is thus imparted as maternal

influence whose direct influence is limited to the nursing period.

The age at first kidding is important because of its effect on the economics of goat

production.

2.2.5 Effect o Year of Kidding on Growth Traits

The effects of season and year of kidding on multiple births, when present, are direct

effects of nutrition through the availability and quality of pasture. Good nutrition is

known to favour a high ovulation rate, which in effect establishes whether there will be

multiple births or not. Kosum et al. (2004) in turkey found out that year of birth was

significant (P<0.01) in their study with Bornova and Saanen x Kilis goat at Turkey. Das et

al. (1996) in Malya reported that year significantly affected birth and weaning weight.

2.2.6 Pre-Weaning and Post-Weaning Growth Rate

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Karua and Banda (1992) in Malawi reported that pre-weaning and post-weaning growth

rates were higher in the Saanen crosses than in the pure locals. They observed that

weight gains per day were higher in males (82.67g before and 41g after weaning) than in

females in the Saanen crosses, but the opposite was observed in pure local kids where

females had higher growth rates of 56g before and 31g after weaning than males having

growth rates of 50g before and 29g after weaning).

Das and Sendalo (1991) in Malya reported that Blended kids showed higher pre-weaning

and post-weaning growth rate. Single-born kids exhibited higher growth rate than the

twin-born kids from birth to weaning and to 24 weeks of age, while at higher ages their

growth rates were not significantly different. Pre-weaning growth rate of 94.3g per day

was recorded for Blended kids in Malya (Das and Sendalo, 1990).

Tuah et al. (1992) in Kumasi recorded overall mean pre-weaning growth rate of 32.88g

per day and Reynolds (1989) recorded 17.4g per day to 31.9g per day for WAD kids in

Nigeria. Tuah et al. (1992) observed that pre-weaning growth was not affected by the

type of birth and he attributed this to the system of raising the kids.

Das et al. (1996) working on Blended goat at Malya reported that year of birth and type

of birth significantly affected the post-weaning weights at 168 days, 336 days and 504

days of age. Season of birth was significant for live weights at 336 days and 504 days

only but not for 168 days of age. The overall average daily pre-weaning and post-

weaning gain at 168 days, 336 days and 504 days of age were 77±1.3g, 59±1.5g and

41±1.0g respectively. Year of birth, sex and type of birth significantly affected average

daily gain from birth to 72 weeks of age. Season of birth had no significant effect on

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average daily gain except at 48 weeks of age. Aganga et al. (2005) reported average

birth weight of the kids as 3.6 kg, while the average daily weight gain was 58g per day in

Botswana. The mean body weights were 8.6±0.6, 15.3±0.8 and 23.3±1.4 kg for the age

group 30 – 120 days, 121 – 240 days and 241 – 360 days, respectively.

Goats do not generally have a high growth rate, compared with lambs. Under

favourable nutritional conditions, Boer goats may gain weight at more than 200 g per

day (Van Niekerk and Casey, 1988). Naud and Hofmeyr ((1981) reported average pre-

weaning growth rates by 54 kids of 227 g per day. Over the entire period the Boer goat

kids grew at 124 g per day, whereas, from birth to 10 kg weight, the rate was 62 g per

day; 10 – 23 kg, 139 g per day; 23 -32 kg, 182 g per day; and 32 – 41 kg, 194 g per day.

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CHAPTER THREE

3.0 Materials and Methods

3.1 Location of Study Area

This study was carried out at the Kintampo Livestock Breeding Station in the Kintampo

district, located at latitude 7°45' and 8°45' North and longitude 1°05' and 2°05' West.

Physically the district is generally hilly in the south and fairly flat and undulating in the

north. It has a single rainy-season from May to October, followed by the dry season

from November to April. It has a mean annual rainfall of between 1000mm to 1200mm.

Mean temperature of the Kintampo district ranges between 20 °C and 36 °C. (Source:

Meteorological Service Department, Kintampo).

3.2 Vegetation

The vegetation in the southern part of the district is of the semi-deciduous forest type.

This vegetation type grades into the wooded savannah type characterized by scattered

shrubs and dawadawa, baoba and sheanut trees in the northern sector (source:

Meteorological Service Department, Kintampo).

3.3 Management of Animals

The Kintampo Goat Breeding Station is one of the six designated to use the ONBS for

goat improvement. The station is to improve upon the WAD goats and sell out to

participatory farmers for multiplication.

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Kids were identified by means of indelible ink from day one to one month of age and

then are tagged and weighed within 12 hours from birth, at weaning (16 weeks) and

yearling age. The kids are weighed with a spring balance whereas adults were weighed

with a lamb weigher. Kids were allowed to be with their mother throughout until

weaning.

Each kid record included sire, dam and kid identification numbers, sex of kid, type of

birth, kidding date, birth weight, weaning weight and yearling weight. Two seasons of

birth were defined on the basis of the monthly rainfall distribution at Kintampo. Rainy

season is from May to October and the dry season is from November to April.

Males are mainly used for selection since the female population is small. The goats are

bred seasonally from September to October and again after March. Matings were

controlled by allowing bucks to join does during a mating period of 45 days every eight

(8) months. In the rainy season does rest for 45 days depending on availability of feed.

Generally batch kidding is practiced on the station. The ratio of males to females is 1:30.

The animals are routinely given anthelminthics. The animals are dewormed every two

months during the rainy season and twice in the dry season. Sick animals are culled and

treated.

3.4 Housing and Feeding

Houses are mainly stalls with concrete floor with gentle slope. Provision has also been

made to prevent draught. Walls of the houses are about 1m high. The goats are housed

in groups according to their age. Kids and dam are housed in the kid sheds up to the

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time of weaning. Adult breeding does are also housed in the general flock shed. There is

a maternity pen for housing pregnant does. This pen is also made to be draught free.

The floor is made of concrete.

The goats are fed on artificial pastures. The station has eleven (11) paddocks with some

being sole pastures and others being mixed pastures. Cynodon dactylon (giant star

grass) is grown as a sole pasture whereas Panicum maximum (guinea grass and

Centrosema pubescens (centrosema) were grown as mixed pastures. Other leguminous

plants include cajanus cajan (pigeon pea) and Stylosanthes sp.. Depending on the size of

the paddock the animals are rotated every two weeks. Animals are allowed to graze ad

libitum in the dry season whiles controlled grazing is practiced during the wet season.

Supplementary salt licks and vitamins are given to the animals during the dry season.

Concentrates made up of maize and soyabean are also fed to the animals. Manihot spp.

(cassava) peels from Ntankoro gari processing village are also fed to the animals.

Soyabean, corn chuff, concentrates, rice bran and pito mash are fed to the females

before crossing.

3.5 Data Collection and Analysis

Data was collected from kid performance records of the Kintampo Goat Improvement

Station (GIS) at Kintampo from 1996 to 2003. After the data was edited for missing

values, mismatched and incorrect values the final data used in the analysis for birth

weight was 944, 875 for weaning weight, 787 for yearling weight, 875 and 787 for pre-

weaning and post-weaning growth rates, respectively. The traits analyzed were birth

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weight, adjusted weaning weight at 120 days, adjusted yearling weight, pre-weaning

and post-weaning growth rates.

The formulae used for adjusted weaning weight and yearling weight traits are as

follows:

1. Adjusted weaning weight at 120 days =

(Actual 120-day weight – Birth weight x 120) + Birth weight Actual age (in days)

2. Adjusted yearling weight =

(Actual 365-day weight – Weaning weight x 365) + Weaning weight Actual age – Weaning weight

Pre-weaning and post-weaning growth rates were calculated using equations 1 and 2

shown below, respectively.

Pre-weaning growth rate= Birth weight – Weaning weight …………equation 1 120 days

Post-weaning growth rate = Weaning weight – Yearling weight ……equation 2 365 – 120 days

Non-genetic factors considered in the analysis were sex of kid, type of birth, parity of

dam, year of kidding and season of kidding. The Generalized Linear Model (GLM)

procedure of SAS (1999) was used for the analysis. Two ways interactions were not

significant hence they were removed from the model.

The statistical model used to relate observations with independent variables was as

follows:

Yijklmn = u +ai + bj + ck + dl +fm +eijklmn…………………….model 1

25

Where yijklmn is the ijklmnth observation on birth weight, weaning weight, yearling

weight, pre-weaning and post-weaning growth rates.

U is an underlying constant, ai is the effect of the ith year of birth (1996 – 2003), bj is the

effect of the jth season of birth (j =1, 2), ck is the effect of the kth parity of dam (k = 1, 2,

3, 4), dl is the effect of the lth type of birth (l = single, twin), fm is the effect of the mth

sex of kid (m = male , female) and eijklmn is random residual error NID (02e).

26

CHAPTER FOUR

4.0 Results

4.1 Kid Body Weight Traits

The analysis of variance table for birth weight, weaning weight and yearling weight is

presented in Table 4.1. Year of birth had significant (P<0.05) effects on all the three

traits. Sex of kid had significant (P<0.05) effect on only birth weight of kid. Parity of dam

had significant (P<0.05) effect on only weaning weight at 120 days and yearling weight.

Season of birth had no significant (P>0.05) effect on any of the traits.

Table 4.1

Analysis of Variance for Birth Weight (kg), Weaning Weight (kg) at 120 days and Yearling Weight (kg)

Source of variance

Degree of freedom

MS for BWT MS for WWT MS for YWT

Year 7 0.23* 2.41* 24.20*

Season 1 0.07 1.37 2.72

Sex 1 1.12* 4.14 0.39*

Type of birth 1 4.26* 26.26* 48.48*

Parity 3 0.09 8.30* 28.48*

Error 775 0.05 -- --

WWT 861 -- 1.22 --

YWT 775 -- -- 3.93

* Significant (P<0.05), MS = Mean Square; BWT = Birth Weight; WWT = Waning Weight;

YWT = Yearling Weight

27

The analysis of variance table for pre-weaning and post-weaning growth rate is

presented in Table 4.2. Year of birth and parity of dam had significant effect on pre-

weaning and post-weaning growth rates. Type of birth had significant (P<0.05) effect on

only pre-weaning growth rate. Season of birth and sex of kid were not significant

(P>0.05) fro pre-weaning and post-weaning growth rates.

Table 4.2

Analysis of Variance for Pre-Weaning Growth Rate (g/day) and Post-Weaning Growth Rate (g/day)

Source of variance Degrees of freedom MS for preADWT MS for postADWT

Year 7 0.14* 0.38*

Season 1 0.17 0.00

Sex 1 0.10 0.04

Type of birth 1 0.66* 0.09

Parity 3 0.46* 0.15*

Error

PreADWT 860 0.07 --

PostADWT 775 -- 0.05

* Significant (P<0.05); MS = Mean Square; preADWT = Pre-Weaning Growth Rate;

postADWT = Post-Weaning Growth Rate

4.2 Birth Weight

Least squares means and standard errors for birth weight are presented in Table 4.3.

The overall mean for birth weight was 1.28 ± 0.01 kg. Type of birth was significant

28

(P<0.05) for birth weight with kids born as singles weighing 1.36 ± 0.01 kg and twins

weighing 1.21 ± 0.01 kg. Male kids weighed heavier (1.32 ± 0.01 kg) than female kids

(1.25 ± 0.01 kg).

Year of birth was significant (P<0.05) for birth weight. Birth weight of kids born in the

dry season (1.27 ± 0.2 kg) was heavier than that of those born in the rainy season ± 0.01

kg). The birth weight of kids born to different parity dams was not significantly (P<0.05)

different. However birth weight of kids born to higher parity dams were heavier than

that of those born to lower parity dams. Birth weight of kids born to fourth parity dams

were the heaviest (1.34 ± 0.04 kg) and kids born to first parity dams were the lowest

(1.25 ± 0.01 kg).

29

Table 4.3

Least Squares Means (L.S.M.) and Standard Error (S.E.) for Birth Weight (kg)

Birth Weight (kg)

Variables No. of observations

L.S.M. S.E.

Overall 944 1.28 0.01

Parity

1 578 1.25 0.01

2 226 1.27 0.02

3 98 1.29 0.02

4 42 1.34 0.04

Type of birth

Single 539 1.36a 0.01

Twins 405 1.21b 0.01

Sex

Male 480 1.32a 0.01

Female 464 1.25b 0.01

Year

1996 82 1.30a 0.03

1997 142 1.25b 0.02

1998 92 1.28a 0.02

1999 74 1.33a 0.02

2000 61 1.23b 0.02

2001 160 1.26c 0.02 2002 151 1.27c 0.02 2003 182 1.37d 0.02 Season Dry 489 1.27 0.02 Wet 455 1.30 0.01

Note: mans within an effect with different letter are significant different (P<0.05)

4.3 Weaning Weight

Least squares means and standard errors for weaning weight at 120 days are present in

Table 4.4. The overall weaning weight of kids was 4.68 ± 0.06 kg. Single born kids

weighed significantly (P<0.05) heavier (4.95 ± 0.06 kg) than twin born kids (4.60 ± 0.07

30

kg). Male kids (4.85 ± 0.08 kg) were heavier than female kids (4.71 ± 0.08 kg) at

weaning. However, the difference in weight was not significant (P>0.05).

Table 4.4

Least Squares Means (L.S.M.) and Standard Error (S.E.) for weaning weight (kg)

Weaning weight (kg) Variables No. of

observations L.S.M. S.E.

Overall 875 4.68 0.06 Parity 1 529 4.52a 0.07 2 213 4.73b 0.12 3 91 5.06c 0.19 4 41 4.80d 0.30 Type of birth Single 509 4.95a 0.08 Twins 365 4.60b 0.07 Sex Male 439 4.85 0.08 Female 365 4.71 0.08 Year 1996 75 4.73a 0.20 1997 127 4.99b 0.15 1998 82 4.77a 0.19 1999 64 4.97b 0.21 2000 55 4.56c 0.12 2001 150 4.67d 0.14 2002 148 4.64d 0.14 2003 173 4.88e 0.15 Season Dry 449 4.83 0.08 Wet 425 4.73 0.07

Note: mans within an effect with different letters are significantly different (P<0.05)

The weaning weight of kids born in different years was significantly (P<0.05) different.

Kids born in the dry season were heavier (4.83 ± 0.08 kg) than those born in the rainy

season (4.73 ± 0.07 kg). The weaning weight of kids born to different parity dams was

significantly different (P<0.05). Kids born to third parity dams were the heaviest (5.06 ±

31

0.19 kg) whereas kids born to first parity dams had the lowest weight at weaning (4.52 ±

0.07 kg).

4.4 Yearling Weight

The least squares means and standard errors for yearling weight are presented in Table

4.5. The overall mean yearling weight at 365 days of kids was 10.94 ± 0.07 kg. Male kids

(11.05 ± 0.11 kg) were significantly (P<0.05) heavier than female kids (11.01 ± 0.10 kg).

Kids born as singles (11.28 ± 0.10 kg) were significantly heavier than those born as twins

(10.78 ± 0.11 kg).

Kids born in different years were significantly (P<0.05). Kids born in the dry season

(11.10 ± 0.11 kg) were heavier than kids born in the rainy season (10.96 ± 0.11 kg).

However, the difference in weight was not significant (P>0.05). The yearling weights of

kids born to different parity dams were significantly (P<0.05) different. Kids born to third

parity dams were the heaviest (11.43 ± 0.36 kg) and kids born to first parity dams being

the lowest (10.47 ± 0.09 kg).

4.5 Pre-Weaning Growth Rate

The least squares means and standard errors for pre-weaning growth arte are shown in

Table 4.6. The overall mean pre-weaning growth rate was 28.38 ± 0.62 g per day. Male

kids had a higher pre-weaning growth (29.51 ± 0.63 g per day) than female kids (28.81 ±

0.60 g per day). However, the difference was not significant (P>0.05). Single born kids

32

Table 4.5

Least Squares Means (L.S.M.) and Standard Error (S.E.) for Yearling Weight (kg)

Yearling Weight (kg) Variables No. of

observations L.S.M. S.E.

Overall 789 10.94 0.07 Parity 1 481 10.47a 0.09 2 187 10.82b 0.16 3 82 11.43c 0.23 4 39 11.40c 0.36 Type of birth Single 464 11.28a 0.10 Twins 325 10.78b 0.11 Sex Male 383 11.05a 0.11 Female 406 11.01a 0.10 Year 1996 67 10.81a 0.28 1997 111 11.34b 0.22 1998 72 10.89b 0.26 1999 53 10.68c 0.21 2000 44 10.21d 0.21 2001 128 10.94b 0.19 2002 146 11.43e 0.16 2003 168 11.94f 0.14 Season Dry 395 11.10 0.10 Wet 394 10.96 0.11

Note: mans within an effect with different letters are significantly different (P<0.05)

had significantly (P<0.05) higher (30.05 ± 0.62 g per day) pre-weaning growth than twin

born kids (28.27 ± 0.56 g per day).

33

The pre-weaning growth of kids born in was significantly (P<0.05) different. The pre-

weaning growth of kids born in the dry season (29.71 ± 0.62 g per day) was higher than

those born in the rainy season (28.61 ± 0.62 g per day). However, the difference was not

significant (P>0.05). Parity of dam also had a significant effect (P<0.05) on pre-weaning

growth rate.

Table 4.6

Least Squares Means (L.S.M.) and Standard Error (S.E.) for pre-weaning growth rate (g/day)

Pre-weaning growth rate (g/day) Variables No. of

observations L.S.M. S.E.

Overall 874 28.38 0.62 Parity 1 529 27.38a 0.54 2 213 28.82b 0.90 3 91 31.53c 0.51 4 41 28.90b 0.59 Type of birth Single 509 30.05 0.62 Twins 435 28.81 0.56 Sex Male 436 29.51 0.63 Female 435 28.81 0.60 Year 1996 75 29.22a 1.51 1997 127 31.18b 1.11 1998 82 29.17a 1.46 1999 64 30.40c 1.60 2000 55 27.67d 0.96 2001 150 28.43e 1.06 2002 148 28.05f 1.02 2003 173 29.14a 1.13 Season Dry 449 29.71 0.62 Wet 425 28.61 0.62

Note: mans within an effect with different letters are significantly different (P<0.05)

34

4.6 Post-Weaning Growth Rate

Table 4.7 shows least squares means and standard errors for post-weaning growth rate.

The overall mean post-weaning growth rate was 26.18 ± 0.30 g per day. There was not

significant different (P>0.05) in the post-weaning growth of kids of different sexes. Male

kids (25.93 ± 0.38 g per day) had lower post-weaning growth than female kids (26.39 ± g

per day). The post-weaning growth rate of single born kids (26.51 ± 0.34 g per day) was

higher than that of twin born kids (25.81 ± 0.36 g per day) though there was no

significant difference (P<0.05).

Table 4.7

Least Squares Means (L.S.M) and Standard Error (S.E) for Post-Weaning Growth Rate (g/day)

Post-weaning growth rate (g/day Variables No. of

observations L.S.M. S.E.

Overall 789 26.18 0.30 Parity 1 481 24.82a 0.33 2 187 25.43b 0.50 3 82 26.76c 0.70 4 39 27.63d 1.08 Type of birth Single 464 26.51 0.34 Twins 325 25.81 0.36 Sex Male 383 25.93 0.38 Female 406 26.39 0.33 Year 1996 67 25.15a 0.90 1997 111 26.63b 0.69 1998 72 25.57c 0.80 1999 53 23.76d 0.54 2000 44 23.93e 0.82 2001 128 26.12f 0.70

35

2002 146 28.56g 0.57 2003 168 29.55h 0.51 Season Dry 395 26.21 0.33 Wet 394 26.11 0.38

Note: mans within an effect with different letters are significantly different (P<0.05)

Year of birth had a significant (P<0.05) effect on post-weaning growth rate. There was

no significant difference (P<0.05) in the post-weaning growth of kids born in different

seasons. Kids born in the dry season had 26.21 ± 0.33 g per day whiles those born in the

rainy season had 26.11 ± 0.38 g per day. Parity of dam had significant (P<0.05) effect on

post-weaning growth rate.

Year of birth had a significant (P<0.05) effect on post-weaning growth rate. There was

no significant difference (P>0.05) in the post-weaning growth of kids born in the rainy

season. Kids born in the dry season had 26.21 ± 0.33 g per day whiles those born in the

rainy season had 26.11 ± 0.38 g per day. Parity of dam had significant (P<0.05) effect on

post-weaning growth rate of kid. Kids born to fourth parity dams had the highest post-

weaning growth (27.63 ± 1.08 g per day) whiles those born to first parity dams had the

lowest (24.82 ± 0.33 g per day).

36

CHAPTER FIVE

5.0 Discussion

5.1 Kid Growth Traits

5.1.1 Birth Weight

The overall mean weight obtain in the study was 1.28 ± 0.01 kg. This closely agrees with

1.11 ± 0.04 kg (ranges 0.45 – 2.5 kg) reported by Tuah et al. (1992). This is however

lower than that reported for other breeds. Das et al. (1996) reported 2.47 ± 0.02 kg birth

weight for Blended goat in Malya Tanzania. Lyatuu et al. (1994) in Malya and Kongwa

reported birth weighs of Blended kids to be 2.34 ± 0.05 kg and 2.31 ± 0.08 kg.,

respectively. Das and Sendalo (1991) also reported 2.1 kg for Indigenous goats and

Kamorai x Indigenous crosses. Aganga et al. (2005) reported a higher average birth

weight of 3.6 kg for Tswana goats in Botswana. The birth weight of WAD kids obtained

in this study falls within the range reported by Tuah et al. (1992) but lower than that

reported for other breeds. The differences in weight of the WAD kids from those of

other breeds may be due to differences of breed, climate and management practices

such as the feeding regime and feedstuffs offered.

5.1.2 Weaning Weight

The overall weaning weight at 120 days of the WAD kids was 4.68 ± 0.06 kg. The

observation in this study was lower than what was obtained by Tuah et al. (1992) who

reported mean weaning weight of 5.19 ± 0.20 kg for the same goat breed in Kumasi.

However this was within the range of 2.5 to 10.0 kg reported by the same authors. Das

37

et al. (1996) reported a weaning weight of 11.14 ± 0.15 kg for Blended goat in Malya.

Lyatuu et al. (1994) reported weaning weights of 12.5 ± 0.12 kg and 11.6 ± 0.34 kg for

Blended goat in Malya and Kongwa, respectively. Aganga et al. (2005) obtained 15.3 ±

0.8 kg weaning for Tswana goat in Botswana. Indigenous and Kamorai x Indigenous

crosses have been reported to weigh 11.7 kg and 17.5 kg respectively by Das and

Sendalo (1991). The lower weaning weights of the WAD obtained in this study may be

due to the inherently slow growth rate associated with the breed (Tuah et al., 1992) as

well as in husbandry practices.

5.1.3 Yearling Weight

The overall mean yearling weight of kids was 10.94 ±0.07 kg. Year 2003 recorded the

highest (11.94 ± 0.14 kg) whiles the lowest was recorded in 2000 (10.21 ± 0.21 kg). The

observation in this study falls below what was recorded by Lyatuu et al. (1994) in their

study with Blended goat. They recorded 28.0 ± 0.73 kg and 27.4 ± 0.16 kg in Malya and

Kongwa at 72 weeks of age respectively. Aganga et al. (2005) also reported a higher

weight of 23.3 ± 1.4 kg at age group of 241 – 360 days for Tswana goats in Gaborne. The

yearling weight obtained in this study was lower than that reported by Pagot (1992).

This may be attributed to the fact that husbandry practices were different for the

various locations. It may also be due to the lower initial weaning weights attained by

kids coupled with the characteristic lower growth rates of the WAD goat.

5.14 Pre-Weaning Growth Rate of Kids

38

The overall mean pre-weaning growth rate was 28.38 ± 0.62 g per day. This observation

is within the range reported by Reynolds (1989) for WAD kids kept in Nigeria (17.4 g per

day to 31.9 g per day). This was however lower than that reported by Tuah et al. (1992)

for the same breed in Kumasi (32.88 g per day). The lower pre-weaning growth obtained

in this study than that of Tuah et al. (1992) may be due to relatively better feeding

regime and other management practices carried out at the university of science and

technology than at Kintampo breeding station.

5.1.5 Post-Weaning Growth Rate

The mean post-weaning growth rate was 26.18 ± 0.30 g per day. This observation was

higher than 24.04 g per day reported by Tuah et al. (1992) and falls within the range of

14 to 28.3 g per day reported by Reynolds (1989). The higher post-weaning growth

obtained in this study than that of Tuah et al. (1992) may be due to more available and

nutritious pasture at Kintampo all year round for weaned kids.

5.2 Effect of Sex of Kid on Kid Growth Traits

Sex of kid was significant (P<0.05) for only birth weight and yearling weight. Males (1.32

± 0.01 kg) were significantly (P<0.05) heavier than females (1.25 ± 0.01 kg) at birth.

Kosum et al. (2004) also reported significant (P<0.01) differences in the sex of kid in

Bornova and Bornova x Killis goats in turkey. Male kids generally had heavier weights at

birth, weaning and at one year of age than female kids. Males also grew faster during

the pre-weaning stage (29.57 ± 0.63 g per day) than female kids. However female kids

39

had higher post-weaning growth rate than male kids. Lyatuu et al. (1994) and Bemji et

al. (1996) reported similar findings in Malya and Kongwa on Blended goat and Yankasa

sheep, respectively. Consistent superiority of males over females has been widely

reported by many authors (Magid et al. 1981; Fitzhugh and Bradford 1983; Kiriro 1986;

Hassan 1987; Osinowo et al. 1990; 1993 and Ikeobi and Faleti 1996). Kassahum (2001) in

their study reported that males were heavier (P<0.001) at birth (2.38 ± 0.03 kg)

compared to females (2.22 ± 0.02 kg) for Horro and Menz sheep in Ethiopia. Assan and

Makuzal (2005) also reported that males (3.32 ± 0.04 kg) were heavier (P<0.05) than

females (3.05 ± 0.07 kg) in indigenous Sabi, 4.73 ± 0.03 kg versus 4.08 ± 0.05 in Dorper

and 4.26 ± 0.07 kg versus 3.66 ± 0.09 kg in mutton merino sheep. These observations

have been attributed to hormonal differences between sexes and their resultant effects

on growth (Velardo, 1958; Bell et al., 1970). Rhind et al. (1980) reported in their study

that the number of cotyledons per foetus may be the same for both sexes but those of

male lambs may be heavier than those of female lambs, thereby prompting the males to

have heavier weight at birth than females because the males obtained relatively higher

supply of nutrients than the females.

Males (4.85 ± 0.08 kg) were heavier than females (4.71 ± 0.08 kg) by 0.14 kg at weaning

age of 120 days. Karua and Banda (1992) also reported similar findings for Saanen

crosses in Malawi. However they reported that females had heavier weight (8.33 ± 0.07

kg) than males (7.60 ± 1.53 kg) at weaning.

Males had a yearling weight of 11.05 ± 0.11 kg and females had a yearling weight of

11.01 ± 0.10 kg. The superiority of males in yearling weight to females is also reported

40

by Lyatuu et al. (1994) in Blended goats in Tanzania and Chawla and Bhatnagar (1983)

for Barbari and Beetal goats in India. The findings of this study also agree with what was

reported for Saanen crosses by Karua and Banda (1992) that males were heavier

(weighing 25.00 ± 3.00 kg) at one year old than females (22.50 ± 1.78 kg).

Inyangala et al. (1992) pointed out that sex of lambs constituted a highly significant

(P<0.001) source of variation for the 365-day body weight in Dorper and Red Massai

sheep. They concluded that this may be due to the superiority of male lambs over

females in term of growth performance.

Pre-waning growth rate of male kids (29.51 ± 0.63 g per day) was significantly (P<0.05)

higher than that of females (28.81 ± 0.60 g per day). This result agrees with those

reported by Karua and Banda (1992) for Saanen crosses who pointed out that weight

gain per day were higher in males (92.32 g) than in females (82.67 g) before weaning.

The reason for their outcome stems from initial differences in birth weight of the two

sexes as reported by Poivey et al. (1982) and Tuahand Baah (1985). Females grew at

relatively faster rate of 0.46 g per day than males during the post-weaning growth stage.

This observation agrees with Kasowanjete et al. ((1987) in Malawi goats and Karua and

Banda (196) in pure local breed in Malawi. This could also be attributed to the effect of

castration.

5.3 Effect of Type of Birth on Kid Growth Traits

The effect of type of birth was significant (P<0.05) for birth weight, weaning weight,

yearling weight and pre-weaning growth rate. However, it was not significant (P>0.05)

41

for post-weaning growth rate. Single born kids performed better in all the traits than

twin born kids. Lyatuu et al. (19940 also reported that birth weight was significantly

influenced (P<0.01) by type of birth. They reported that birth weight decreased with

increased litter size. Single born kids were 5.8% heavier than twin born kids at birth.

Twins had lower birth weighs than singles, probably due to their smaller size and weight

in the uterus. Kosum et al. (2004) and Kassahum (2001) also reported that type of birth

was significant (P<0.01) for lamb birth weight. The reason for this observation is given

by Robinson et al. (1977) was that for lambs in utero, as the number of fetuses

increases, the number of caruncles attached to each foetus decreases thus reducing the

feed supply to the foetus and hence the birth weight of the lambs.

It was however, observed that the combined weight for wins was higher than that for

singles. Godwin (1971) also observed that twins and triplets are smaller at birth than

singles but their total weight may be more.

The significance (P<0.050 of type of birth on pre-weaning growth rate in this study

disagrees with that reported by Tuah et al. (1992) working on the WAD goat in Kumasi.

They reported that type of birth was not significant (P>0.05) for pre-weaning growth

rate. They recorded 33.1, 31.6 and 29.0 g/day for singles, twins and triplets respectively

were not affected by type of birth. Lyatuu et al. (1994) reported that type of birth was

not significant (P>0.05) for pre-weaning growth in the Blended goat. They explained that

because most of the kids were raised as singles and twins. The observation in this study

was however contrary to Odobute (1992) who observed that in WAD ewes, twins and

triplets were heavier than singles.

42

At weaning, single born kids were significantly heavier (4.95 ± 0.08 kg) than twin born

kids (4.60± 0.07 kg). This observation agrees with Das et al. (1996) and Sidwell et al.

(1962), who reported that type of birth had significant (P<0.05) effect on weaning

weight. Though type of birth was not significant (P>0.05) for post-weaning growth rate.

Single born kids grew faster than twin born kids. This generally agrees with the

observation by Robinson et al. (1977).

Single kids had sufficient milk for growth to weaning and so higher weights at maturity

for single kids could be explained by this initial advantage and the positive correlation

between weaning and mature weight (Lyatuu et al., 1994).

5.4 Effect of Season of Kidding on Kid Growth Traits

Season of birth was not significant (P>0.05) for all the traits studied. Apart from birth

weight, kids born in the dry season performed better in all other traits than those born

in the wet season. This observation also agrees with Das et al. (1996) in Blended goat at

Malya. The birth weight of kids born in the dry season was lighter (1.27 ± 0.02 kg) than

kids born in the wet season (1.30 ± 0.01 kg). This observation is contrary to Lyatuu et al.

(1994) who reported that dry season born kids were heavier than rainy season born kids

in Blended goat. The effect of season of birth arises from seasonal variation in the

physical environment resulting from changes in weather conditions including rainfall

amounts, temperature and humidity, which directly affect fed availability (Lyatuu et al.,

1994).

43

Seasonal influence on a trait such as birth weight operates through its effect on the

dam’s uterine environment mostly in late gestation (Eltawil et al., 1970). Such factors

operating in seasons prior to lambing will be manifested in birth weight. This explains

the higher birth weight of kids born in the dry season. It is, therefore, expected that the

season when the doe is in gestation I likely to play a more important role in birth than

the actual season of birth. The observation in this study can be explained by the fact

that there was poor nutrition of pregnant does during the dry season resulting in the

decreased birth.

Kids born in the dry season were 0.10 kg heavier than kids born in the wet season at

weaning. The result of this study agrees with reports made by Das and Sendalo (1991),

Inyangala et al. (1992) and Lyatuu et al. (1994).

Generally kids born in the dry season obtained heavier weaning weights. This could be

attributed to the availability of browses and shrubs in the dry season that had higher

protein and energy content. Kids prior to weaning depend mainly on the dam’s milk as

food, the production of which is directly related to the availability of nutritious feeds to

the does (Mukundan and Bhat, 1983; Groot et al., 1993).

Yearling weights of kids were higher for kids in the dry season (1.10 ± 0.10 kg) than

those born in the wet season (10.96 ± 0.11 kg). The significance of season of birth for

early growth performance may thus be responsible, as a carryover effect, for its

significant influence on growth traits up to yearling weight (Inyangala et al., 1992).

Kids born in the dry season grew faster (29.71 ± 0.62 g per day) than those born in the

wet season (28.62 ± 0.62 g per day) before weaning. This observation agrees with that

44

by Inyangala et al. (1992) in Dorper lambs. This may be due to the higher body weights

attained at birth, which is contrary to what was observed in this study. Dry season kids

growing at 26.21 ± 0.33 g per day had faster growth rates than rainy season born kids

growing at 26.11 ± 0.38 g per day.

Season did not affect significantly (P<0.05) post-weaning growth of kids. This closely

agrees with Das et al. (1996). Das et al. (1996) also reported that season of birth was not

significant on average daily gain except at 48 weeks of age in Blended goat at Malya. In

the post-weaning periods the influence of season is related to its effect on the quality

and quantity of pasture available to the weaned kids (Das et al., 1996). However post-

weaning growth rates of kids born in the dry season (26.21 ± 0.33 g per day) was lighter

than that for kids born in the wet season (26.11 ± 0.38 g per day). This is contrary to that

by Ikeobi and Faleti (196). Ikeobi and Faleti (1996) reported that mean weekly gain in

the liveweight of goats was 0.18 ± 0.02 kg in the dry season and 0.26 ± 0.05 in the wet

season and that goat liveweight in the wet season was 38% greater than the figure in

the dry season.

The post-weaning growth rate was lower since the early post-natal phase of growth in

goats is a critical stage because this is the stage when there is little maternal protection

and the kid is exposed to environmental stress which limits its growth rate (Das et al.,

1996). The rate of growth of a kid after weaning, however, is partly determined by the

genetic potential of the kid and the level of environmental influence, especially during

the immediate post-weaning stage. Degen and Young (1981) also reported that total

45

intake of dry matter was significantly lower in the dry season than in the wet season and

attributed this to the depressing effect of high ambient temperature on feed intake.

5.5 Effect of Year of Birth on Growth Traits

Year of birth was significant (P<0.05) for all traits in the study. This observation agrees

with the reported by Kosum et al. (1996). Das et al. (1996) in Malya also reported that

year significantly affected birth and weaning weight. The heavier kids at birth were

recorded in 2003 (1.37 ± 0.02 kg 0 whiles the lowest was recorded in 2000 (1.23 ± 0.02

kg).

Assan and Makuzal (2005) also observed that year of lambing had significant effects

(P<0.05) on birth weight in indigenous Sabi, mutton merino and Dorper sheep. Bemji et

al. (1996) and Osinowo et al. (1992) also reported that year of birth was a highly

significant (P<0.001) source of variation in birth weight of Yankasa sheep in Shika,

Nigeria. Kosum et al. (2004) in turkey found out that year of birth was significant

(P<0.01) in their study with Bornova and Saanen x Kilis goats. Inconsistent yearling

variation in body weights at birth has been observed by Kantharaji et al. (19981), Adu et

al. (1985), Buvanendran et al. (1992) and Osinowo et al. (1992). This could be accounted

for by variation in general husbandry practices between years (Adu et al., 1985). In

addition the differences relate to the individual reports that yearly effects on growth

performance are unique or specific to the individual years.

Figure 5.1 illustrates the trend of birth weight, weaning weight and yearling weight over

the years of study.

46

Figure 5.1 Trend of Body weights of Kid over the Year of Study

From figure 5.1 the highest weaning weight of kids was recorded in 1997 (4.99 ± 0.15

kg) whereas the lowest was recorded in 2000 (4.56 ± 0.12 kg).

Pre-weaning growth rate of kids differed within the years. The highest rate was in 2002

and the lowest was in 2003. Post-weaning growth of kids also varied with year of birth.

Figure 5.2 represents the trend of pre-weaning and post-waning growth of kids over the

years of study.

1.3 1.25 1.28 1.33 1.23 1.26 1.27 1.37

4.73 4.99 4.77 4.97

4.56 4.67 4.64 4.88

10.81 11.34

10.89 10.68 10.21

10.94 11.43

11.94

0

2

4

6

8

10

12

14

1996 1997 1998 1999 2000 2001 2002 2003

Year of Birth

Birth Weight Weaning Weight Yearling Weight

We

igh

t (kg

)

47

Figure 5.2 Trend of pre-weaning and post-weaning growth rates over the years of study

Das et al. (19960 observed in Blended goats in Malya that year of birth had significant

(P<0.05) effect on post-weaning growth from birth to 24, 48 and 72 weeks of age. They

explained that the differences in both pre-weaning and post-weaning growth rates over

the years result from variation in the amount of rainfall which in turn influences pasture

production and availability of feed.

5.6 Effect of Parity on Kid Growth Traits

Parity of dam was significant (P<0.05) for weaning weight, yearling weight, pre-weaning

and post-weaning growth rates but was not significant (P>0.05) for birth weight of kids.

Though the effect of parity was not significant (P>0.05) for birth weight, those born to

29.22

31.18

29.17 30.4

27.67 28.43 28.05

29.14

25.15 26.63

25.57 23.76 23.93

26.12

28.56

29.55

0

5

10

15

20

25

30

35

1996 1997 1998 1999 2000 2001 2002 2003 Year of Birth

Gro

wth

rate

(g/d

ay

Post-weaning Growth rate Pre-weaning Growth rate

48

higher parity dams weighed (1.34 ± 0.04 kg) heavier at birth than those born to first

parity dams (1.25 ± 0.01 kg).

The heavier weaning weight was obtained for kids born to third parity (5.06 ± 0.19 kg)

dams with those born to first parity (4.52 ± 0.07 kg) dams being the lightest.

The yearling weight of kids born to first parity dams was the lightest (10.47 ± 0.09 kg)

whereas those born to third parity dams (11.43 ± 0.23 kg) were the heaviest. The

explanation for this observation could be due to the generally held view that kids born

to higher parity dams tend to have heavier weights than those born to lower parity

dams (Abassa et al., 1992; Hafez, 1980 and Bemji et al., 1996). Hafez (1980) advanced an

explanation that reproductive efficiency is not fully attained at first oestrus and it is

generally known that mothering ability, especially milk production increases with parity.

In addition older ewes are larger in body and are better milkers (Das and Acharya,

1970); Eltawil et al., 1970; Wright et al., 1975; Stobart et al., 1986). The report by

Buvanendran et al. (1981) also agrees with the findings in this study. They indicated that

at six months of age when lambs are independent of the maternal milk supply, the

influence of dam age or parity was considerably less and non significant.

The pre-weaning growth rate of kids born to first parity dams (27.38 ± 0.54 g per day)

was lowest whereas those born to third parity dams (31.53 ± 0.51 g per day) had the

highest. With regards to the post-weaning growth rate that of kids born to first parity

dams (24.82 ± 0.33 g per day) was whereas those born to fourth parity dams (27.63 ±

1.08 g per day) was the highest.

49

Pre-weaning growth rate and post-weaning growth rates of kids increased with parity of

dam. This may be because first parity ewes are still growing and thus must provide for

their own growth in addition to the foetal demand. The explanation for this observation

could be due to generally held view that kids born to higher parity dams tend to have

heavier weights than those born to lower parity dams (Abassa et al., 1992; Hafez, 1980

and Bemji et al., 1996). Inyangala et al. (1992) in their study on Dorper sheep observed

that the influence of superior maternal environment of ewes is expected to be

translated into better lamb performance up to weaning. From the study the pre-

weaning growth was however higher than the post-weaning growth.

50

CHAPTER SIX

6.0 Summary, Conclusion and Recommendations

6.1 Summary

The study was carried out at the Kintampo goat breeding station located in the Brong

Ahafo region to examine the effect of some non-genetic factors on growth traits of the

West African Dwarf (WAD) goat. Kid performance data collected over a period of eight

years (1996 – 2003) was analyzed using the GLM procedure of Statistical Analysis

Systems (SAS) (1999). Means of non-genetic factors that were significant for some of the

kid growth traits were separated using the Least Significant Difference (LSD) of GLM.

The non-genetic factors considered in the study were sex of kid, parity of dam, year of

birth, season of kidding and type of birth. The growth traits considered in the study

were birth weight, weaning weight, yearling weight, pre-weaning growth rate and pos-

weaning growth rate.

The overall means were 1.28 ± 0.01 kg for birth weight, 4.68 ± 0.06 kg for weaning

weight, 10.94 ± 0.07 kg for yearling weight, 28.38 ± 0.62 g per day for pre-weaning

growth rate and 26.18 ± 0.30 g per day for post-weaning growth rate from weaning to

yearling age.

Year of birth was significant (P<0.05) for all the traits. Season of birth was however not

significant (P>0.05) for the entire trait. Type of birth was a significant (P<0.050 source of

variation for only birth weight, weaning weight, yearling weight, pre-weaning growth

rate. It was not significant (P>0.05) for post-weaning growth rate of kids. Parity of dam

was a significant (P<0.05) source of variation for all the growth traits considered in the

51

study except birth weight of kid. Sex of kid was not significant (P>0.05) for weaning

weight, pre-weaning growth and post-weaning growth rates of kid. However, it was

significant (P<0.05) for birth weight and yearling weight.

Year of birth effects were varied for all the traits. This is due to the specific and unique

characteristics peculiar to individual years. Kids born in the dry season were significantly

(P<0.05) heavier at weaning, yearling age as well as higher pre-weaning and post-

weaning growth rates than kids born in the wet season. However for birth weight of

kids, those born in the rainy season were heavier than those born in the dry season.

These observations may be attributed to the fact that pregnant does in the rainy season

had good nutrition, hence the heavier weights and growth during the dry season. Single

born kids grew faster before and after weaning and also had heavier body weights than

twin born kids.

With respect to parity of dam, it was generally observed that the widely held view that

kids born to higher parity dams performed better than those born to lower parity dams

was clearly observed in all the traits.

With respect to sex of kid, male kids had heavier birth weight, weaning weight, yearling

weight and grew faster before weaning than female kids. After weaning, female kids

grew at a faster rate than male kids.

6.2 Conclusion

The mean weights and growth rates obtained in the study compares favourably with

similar studies conducted in the same climatic zone for the West African Dwarf goat.

52

The study shows that the non-genetic factors influence the phenotype of the WAD goat

greatly. These environmental factors must be evaluated and adjusted for in breeding

programmes.

From the study adjustment factors have to be developed for non-genetic factors, which

were significant for some of the traits. Adjustment for these significant effects will help

in estimating genetic parameters such as heritability, genetic and phenotypic

correlations that are guides to selection in livestock programmes.

6.3 Recommendation

The following recommendations are suggested:

1. Since the selection of animals in the Kintampo goat breeding station is based on

the breeding value of an animal, routine adjustment of the environmental

factors affecting the animals should be done to help in heritability estimation,

needed for calculating breeding values of traits.

2. Computerization of the station’s operations as well as proper identification of

animals should be embarked upon and

3. To the department of animal science, it is recommended that further studies

should be carried out in other breeding stations

53

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