ABSTRACT
Twenty-five intensively managed mature West African Dwarf goats were used for the experiment
comprising 20 Does (dams) and 5 bucks (sires). The goats were classified into 5 mating pens of 4
Does (dams) and one buck (sire) randomly assigned per pen. Fresh water and forage were provided
ad libitum in addition to 1kg concentrates Cajanus cajan to each animal per day. Data were collected
on weights at birth and weaning; litter size and linear body measurements. Body weight gain was
calculated. The data were subjected to analysis of variance in completely randomized design using
the statistical package of social science (SPSS) computer package. The Paternal Half-sib Analysis
model was used to estimate sire component of variance from which the additive genetic variance and
heritability were calculated. The descriptive statistics (mean ±S.E) and Coefficient of Variation for
birth weight, litter size, body weight gain and body weight showed that birth weight of the offspring
were significantly different (P<0.05) between sires. The weaning weight of offspring of different sire
groups indicated non-significant differences (P>0.05). Body weight gain of sires group recorded
significant differences (P<0.05). The effect of sex of the animal body weight, body weight gain,
body length, arm length and height at wither showed that male progenies were higher than females;
while the effect of season of birth indicated that kids born in dry season had higher daily weight gain
(44.16±3.11g) than those born in wet season (42.32±3.74g). The heritability estimates for birth
weight, litter size and weaning weight were low, moderate and high (0.15, 0.22 and 0.88),
respectively. The estimates of heritability for body length at birth were moderate, while at 6 months
of age the heritability was high (0.95) and this indicates high potence for genetic improvement.
Linear body measurement traits (body length, arm length, and height at wither) recorded high
heritability values. Phenotypic, genotypic and environmental correlations between pairs of
parameters in West African Dwarf goat traits ranged from -0.01 to 0.99.
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TABLE OF CONTENTS
Certification…………………………………………………….……………….i
Dedication………..…………………………………………………………….ii
Acknowledgement…………………………………………………………….iii
List of Table…………………………………………………………………….iv
Abstract…………………………………………………………………………v
CHAPTER ONE: INTRODUCTION
1.1 Objective of the Study……………………………………………………2
1.2 Problem Statement……………….……………………………………….2
1.3 Justification……………………………….………………………………3
CHAPTER TWO: LITERATURE REVIEW
2.1 West African Dwarf Goat Breeds………………………………………….4
2.2 Importance of Goats…………………………………..……………………4
2.3 Indigenous Breeds of Goats……………………………..………………….5
2.4 Environmental Factors that Influence Economic Traits………… …………6
2.4.1 Birth Weight…………………………………………………………..……6
2.4.2 Weaning Weight……………………………………………………..……..8
2.4.3 Litter Size…………..……………………………………………………. 9
2.5 The Genetics of Economic Traits of Farm Animals……………… 10
2.6 Growth and Reproductive Traits of West African Dwarf Goats…… 11
2.6.1 Growth……………………………………………………………….….…11
2.6.2 Body Weight……………………………………………..………………. 12
2.6.3 Body Weight Gain….……………………………………………………. 13
2.7 Body Measurement and Body Weight………………………………. 14
2.8 Genetic Relationship between Traits……………………………… 14
2.9 Genetic Parameters for Birth Weight……………………………… 17
2.9.1 Heritability…………………………………………………………..…….. 17
CHAPTER THREE: MATERIALS AND METHOD
3.1 Location of the Study……………………………………………………. 18
3.2 Experimental Animals……………………………………………………. 18
3.3 Housing of the Animals………………………………………………….. 18
3.4 Experimental Design…………………………………………………… 18
3.5 Management of Experimental Animals………………………….…….18
3.6 Management of Pregnant Does…………………………………….….. 19
3.7 Data Collection……………..…………………………………………….… 19
3.8 Data Analysis……..……….…………………………………………………20
3.8.1 Genetic Analysis……………………………………………………………20
3.9 Genetic Phenotypic and Environmental correlation…..……………. 21
3.9.1 Genetic Correlation (rG)……………………………………………………. 21
3.9.2 Phenotypic Correlation (rP)………………………………………………. 21
3.9.3 Environmental Correlation (rE)……………………………………………. 22
CHAPTER FOUR: RESULTS AND DISCUSSION
4.1 Monthly Body Growth Performance.……..………………….…………… 25
4.2 Effect of Season of Birth and Sex of Animal…………………………….27
4.3 Variance Components for performance Traits………………………………30
4.4 Heritability Estimates ……………………………………………………… 31
4.4.1 Heritability Estimates for Reproductive Traits ……….……………… 31
4.5 Phenotypic, Genotypic and Environmental Correlation ………… 32
4.6 Comparison between Sires for Performance Traits …………………..34
CHAPTER FIVE: SUMMARY, CONCLUSION AND RECOMMENDATION
Summary, Conclusion and Recommendations ……………………………36
REFERENCES ……………………………………………………………………38
APPENDIX………………………………………………………………………………………………51
CHAPTER ONE
INTRODUCTION
The 2006 national census gave the population of Nigeria as 144 million people (National
Population Commission, 2006). With the rate of population growth and rapid loss of indigenous
livestock species coupled with rising costs of production, the present gap in the supply of animal
protein is bound to widen. To bridge the animal protein demand and supply gap, the Nigeria
government since 1970s to date, has attempted to improve indigenous breed of livestock by
importing exotic breeds. These efforts have failed principally because the exotic breeds could not
adapt to the tropical Nigerian environment as the challenges of tropical pests and diseases were
unbearable to them. Locally adapted breeds (indigenous breeds) are better able to survive and
produce valuable products in low input and variable environments (AGRI, 2002).
Maijala (1983) reported that genetic improvement is currently being conferred on
indigenous breeds of goats because they have long been adapted to extreme harsh environmental
conditions of nutrition, climate and disease. They might be more productive in their own
environment than exotic breeds. They can also be valuable experimental animals in fundamental
research and a potential store of unique genes, which may be useful especially when
environment concerns necessitate changes in production system (Salako and Ngere, 2002). The
indigenous small ruminant populations in Nigeria comprising sheep and goats are important
genetic sources because of their adaptation characteristic such as hardiness to the stressful
tropical environment and trypano-tolerance (Salako, 2004). Of the several breeds of goats in the
world, the predominant breed in the humid tropics is the West African Dwarf goats. The majority
of these are bred under the traditional management and their contribution to the total supply of
meat in the region is enormous.
The ability of farmers and buyers to relate the live animal measurements to growth
characteristics is essential for optimum production and value-based trading system. This ability
will also adequately reward livestock farmers rather than the middlemen that tend to gain more
profit in livestock production business especially in developing countries (Afolayan et al., 2006).
A study of linear body measurements on most farms in the tropics is important because most
farmers lack weighing scales and the education to understand their manipulations (Gerald, 1994).
Linear body measurements can be used as a way of estimating weight and market value in terms
of cost of the animals (Gerald, 1994).
1.1 Objectives of the Study
The general objective of this study was to determine the genetic parameters of growth and
reproductive traits of West African Dwarf (WAD) goats reared in the humid tropics.
The Specific Objectives are:
· To evaluate the West African Dwarf (WAD) goats for growth performance.
· To determine the effect of sex and season on performance traits of West African Dwarf
goat.
· To determine the heritability of litter size, growth and body measurements in West
African Dwarf (WAD) goat.
· To determine the genetic, phenotypic and environmental correlations between body
weight and body measurements at various ages.
1.2 Problem Statement
Animal agriculture provides the animal protein needs of Nigeria (Ogbu, 2010). This is an
enormous responsibility. The British Medical Association recommends a minimum animal
protein intake of 34g per caput per day (Okunenye, 2002). According to Ogbu (2010), the
average animal protein intake per caput per day in Nigeria was 7.6g .The Central Bank of
Nigeria (2000) while analyzing the economic sub-sectors noted that the Gross domestic product
(GDP) has been on a downward trend. The nature of GDP reflects the standard of living of the
citizens; it means that the standard of living of Nigerians has been on the decline. This implies
that the animal protein intake of the average Nigerian has to fall far below the recommended
levels. To make up for this decline, Nigeria must import animal milk and meat products from
other countries. Ironically, in spite of the enormous number of indigenous livestock resources,
Nigeria remains a net importer of livestock products since the 1980s (Okunenye, 2002).
There has been a total neglect of indigenous species of livestock, as a result they have
remained undeveloped. It is, therefore, imperative that efforts be channeled towards the
improvement of West African Dwarf goat which is indigenous to the tropics. Improvement in the
growth traits and reproductive performances of the West African Dwarf goat will increase its
carcass yield and enhance its acceptance as a meat animal and as well increase farmer’s income.
1.3 Justification
Improvement in West African Dwarf (WAD) goats would go a long way towards
increased resources of quality and quantity of meat and milk, which provide animal protein that
are indispensable to a balanced human diet. Meat is the primary purpose for which goats are kept
in Nigeria. Among the ruminants, goats are more prolific than cattle. High prolificacy coupled
with short generation intervals offer a quicker means of bridging the gap currently existing in
animal protein consumption in the country. To optimize gains from environmental influences,
genetic parameters and attributes of the animal for economic traits should be appraised regularly.
This is because the size of an animal is always considered in relation to its age allowing
for evolution of growth performance used as a component in deciding which animal to buy, sell,
cull, or mate. Properly calibrated livestock scales are the most accurate and consistent method for
determining body weight. Under farm conditions, where scales and record may be absent, it may
be difficult to know the weight and age of goat. Linear measurement of animals, in addition to
providing body size, can be used to estimate weight. Change in dentition of goats from birth to
maturity can be used to estimate age. The weight of a goat fluctuates as a result of management
system, pregnancy, gut fill, lactation (Awgichew and Abegaz, 2009).
This study intends to investigate the genetic parameters of growth and reproductive traits
of West African Dwarf (WAD) goat population reared in the humid tropics.
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