GENETIC PARAMETERS OF GROWTH AND REPRODUCTION IN THE WEST AFRICAN DWARF GOATS REARED IN THE HUMID TROPICS

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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

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.

CHAPTER 1

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

GENETIC PARAMETERS OF GROWTH AND REPRODUCTION IN THE WEST AFRICAN DWARF GOATS REARED IN THE HUMID TROPICS