The effects of.-casein, beta-lactoglobulin, prolactin and DGAT1 polymorphisms on milk yields in Turkish Holstein cows

The aim of this study was to determine the effects of kappa-casein, beta-lactoglobulin, prolactin, and DGAT1 (diacylglycerol acyltransferase1) gene polymorphisms on milk yields in Holstein cows raised in Antalya province, Turkey. A total of 517 cows were genotyped by the PCR-RFLP method to detect kappa-casein/HinfI, beta-lactoglobulin/HaeIII, prolactin/RsaI, and DGAT1/Cfr1 polymorphisms. In the study, two types of alleles were identified as A and B for kappa-casein, beta-lactoglobulin, and prolactin loci, while K and A alleles were detected for DGAT1 locus. The frequencies of A and B allele were calculated as 0.8279 and 0.1721 for kappa-casein, 0.4662 and 0.5338 for beta-lactoglobulin, 0.8762 and 0.1238 for prolactin, respectively. The frequencies of the K and A allele were 0.6441 and 0.3559 for DGAT1. The studied population was found to be in Hardy-Weinberg equilibrium for all of the loci. Association analysis revealed a significant effect of prolactin-RsaI polymorphism on milk yield (p < 0.05) in which animals with the B allele showed superior value than the A allele. On the other hand, no statistically significant relation effects of kappa-casein-HinfI, beta-lactoglobulin-HaeIII, and DGAT1-CfrI polymorphisms on milk yield were observed (p > 0.05). It would be beneficial to increase the number of studies that determine the variation of existing genes and investigate the effects of these polymorphisms on milk yield characteristics in Holstein cattle. Thus, obtained results can be used as a selection criterion in marker-assisted selection programs.