The effect of Kappa casein polymorphism on milk production traits in Brown Swiss cattle

Today, with the help of molecular genetics, it has been possible to study candidate genes, which have influence on quantitative traits. Kappa casein is one of the important proteins in milk that any of its polymorphism leads to difference in milk production traits. In this study, blood samples were collected from ninety one Brow Swiss cow and their DNA was extracted by modified salting out procedure. They were genotyped for the SNP of exon IV by PCR-RFLP method. Breeding values of cows were individually predicted for milk production, fat and protein milk percent traits. Association between polymorphisms and breeding values were investigated by generalized linear model at 5 percent significant level. Frequencies of AA, AB and BB genotypes were 0.19, 0.35 and 0.46, as well as, the allele frequencies of A and B were 0.365 and 0.635, respectively. Chi-square test indicated deviation from Hardy-Weinberg expectation (P<0.05). There was no significant association between genotypes and breeding values of milk production, fat and protein percent traits.