Genetic variability of Nigerian Sheep breeds based on the leptin gene locus

Abstract

The genetic variability of sheep based on the leptin (exon 2) gene was evaluated. One hundred and sixty sheep comprising of 60, 50 and 50 of Yankasa (YB), Balami (BB) and Uda (UB) sheep respectively were used for the study. The genotypic frequencies of GG and GA were observed with the following valued of 0.5968 and 0.4032, 0.7105 and 0.2895 and, 0.5625 and 0.4375 for YB, BB and UB breeds, respectively. Corresponding frequencies of alleles were 0.7984 and 0.2016, 0.8553 and 0.1447 and, 0.7813 and 0.2188 for G and A respectively. The frequency of G allele and genotype GG was higher than that of A allele and genotypes GA for all the breeds. The Chi square test showed that genotypic distributions in all the population were within Hardy-Weinberg equilibrium for the studied populations (P > 0.05). Level of genetic diversity was observed of the gene locus. The observed heterozygosity for YB, BB and UB were 0.678, 0.752 and 0.658 respectively. The corresponding expected heterozygosity was 0.322, 0.248 and 0.342 for YB, BB and UB respectively. The expected heterozygosity (He) values were consistently lower than the observed heterozygosity (Ho). The higher values of observed heterozygosity indicated a relatively high level of genetic diversity of leptin exon 2 genes among the population. The Polymorphic Information Content (PIC) of 0.27 and 0.28 were observed in Yankasa and Uda breeds, Balami breed had lower value of 0.21. In conclusion the leptin locus for the three populations varied, Y and U population had moderate level of polymorphism information content. The molecular phylogenic analysis suggested that YB and UB breeds had closer association.