Growth hormone gene polymorphism and its association with lactation yield in dairy cattle*

Abstract

Kankrej, Gir and Holstein were typed for 3 growth hormone loci to identify the expected RFLP (restriction fragment length polymorphisms) markers in exon fifth (GH1 locus), intron third (GH2 locus) and 3' region (GH3 locus) of the gene with AluI, MspI and HaeIII restriction enzymes, respectively. The Kankrej breed was monomorphic at GH1 locus. The alleles A, D and F at 3 GH loci were more frequent in Kankrej and Gir cows, while the frequencies of their alternative alleles were comparatively more in Holstein cows. B and C alleles of GH1 and GH2 loci, respectively, appeared to be significantly associated with higher lactation milk yield. The cows with AB and BB genotypes at GH1 and CD and DD genotypes at GH2 locus yielded more or less same first lactation milk indicating complete dominance of b and D alleles overA md C alleles, respectively. The genotypes at GH3 locus were independent of lactation yields. The phylogenic tree based on genetic distances indicated that Kankrej and Gir belonged to close cluster while Holstein belonged to different cluster.