Relationship between kappa-casein polymorphism and production traits in Brown Swiss and Holstein

To study the effect of kappa-casein polymorphism on milk production traits, milk samples from Brown Swiss, Holstein and East Anatolian Red cows were analyzed for kappa-casein, AA, AB and BB variants using horizontal starch-gel electrophoresis. Differences among breeds studied were not significant on gene variants. Although the effects of kappa-casein phenotypes on fat percentage and 305d fat yield in Brown Swiss and Holstein cows were found to be significant (P < 0.01 and P < 0.05, respectively), there was no effect on milk yield, 305d milk yield, lactation period and Milk fat yield. This study provides evidence that production and percentage of fat ratio can be maximized by the use of kappa-casein BB genotype and milk Production by the use of kappa-casein AB genotype with selective goal in herds and increase in frequency of kappa-casein B genes in herd could contribute to significantly improve yield traits.