Genetic Parameters of Growth and Reproduction in the West African Dwarf Goats Reared in the Humid Tropics.
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;
Introduction
Background of Study
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.
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