Phenotypic and genetic characterization of qualitative traits in the West African Dwarf goat of Ghana

Abstract

A study was conducted to characterize the West African Dwarf (WAD) goat populations in four agro-ecological zones of Ghana for some major qualitative traits. A total of 1,384 matured goats were sampled. The goat populations were characterized in terms of coat colour and colour pattern, presence or absence of wattle, horn and beard. The animals were individually observed for the presence of alleles for light coat colour (Ror), wattle (Waw), beard (Brb) and horn (Hoh). The frequencies of these alleles were obtained from a count of the proportion of recessives in the population using the Hardy-Weinberg rule. The observed allele frequencies were tested against the expected Mendelian values of 0.75 and 0.25 for dominant and recessive alleles using Pearson's chi-square test. The phenotypic differentiation was analyzed using frequencies of phenotypes while genetic diversity was studied using gene frequencies, heterozygosity and genetic distances. Results obtained showed the presence of varied coat colours and patterns among the goat populations studied. Again, with the exception of the allele for horn presence, the dominant alleles for wattle, beard and light coat colouration in all the four populations were found to segregate at low frequencies, hence the need to preserve these traits from the risk of extinction. Within population, heterozygosity ranged from fairly low to high for wattle, beard and light coat colouration respectively. Apart from the wattle loci which recorded comparatively higher genetic distance between the Transitional and the Rain forest zones, low genetic distances were obtained for the other traits.