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="" differences="" different="" groups="" indicated="" non-significant="" of="" offspring="" sire="" sires.="" the="" weaning="" weight="">0.05). Body weight gain of sires group recorded significant differences (P<0 .05="" 0.22="" 0.88="" 6="" age="" and="" animal="" arm="" at="" birth="" body="" born="" daily="" dry="" effect="" estimates="" females="" for="" g="" gain="" genetic="" had="" height="" heritability="" high="" higher="" improvement.="" in="" indicated="" indicates="" kids="" length="" litter="" low="" male="" moderate="" months="" of="" potence="" progenies="" respectively.="" season="" sex="" showed="" size="" span="" than="" that="" the="" this="" those="" was="" weaning="" weight="" were="" wet="" while="" wither="">
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
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.....
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