DNA polymorphisms of κ-casein, β-lactoglobulin, growth hormone and prolactin genes in Korean cattle

The gene and genotypic frequencies of kappa-casein (kappa-CN), beta-lactoglobulin (beta-LG), growth hormone (bGH) and prolactin (bPRL) loci in Korean cattle were investigated using PCR-RFLP analyses. Genomic DNA samples were obtained from 290 cows and 30 AI bulls. In both cows and bulls, the most predominant genotypes of kappa-CN, beta-LG, bGH and bPRL loci were AB, BE, AA and AA, respectively. The frequencies of A and B alleles for kappa-CN locus were .612 and .388 for cows and .567 and .433 for bulls. The respective frequencies of A and B alleles for beta-LG locus were .153 and .847 in cows and .217 and .783 in bulls. The frequencies of A and B alleles for bGH locus were .769 and .231 in cows and .784 and .216 in bulls, respectively. The frequencies of A and B alleles for bPRL locus were .678 and .322 for cows and .767 and .233 for bulls. Differences in frequencies of these alleles were not significant between cows and bulls at all loci examined. If the DNA polymorphisms of these candidate genes are associated with economically important traits, they could serve as genetic markers for genetic improvement in future marker-assisted selection programs in Korean cattle.