Relationships between beta-lactoglobulin and beta-casein Polymorphisms and production traits in brown swiss and holstein

To study the effects of Beta-Lactoglobulin (beta-Lg) and Beta-Casein (beta-Cn) polymorphism on milk production traits, milk samples from Brown Swiss, Holstein and East Anatolian Red cows were analyzed for beta-Lg and beta-Cn AA, AB and BB types using horizontal starch-gel electrophoresis method. Differences of both beta-Lg and beta-Cn among breeds studied in terms of proportion of phenotype were significant on gene variants. While effects of beta-Cn phenotypes on studied yield traits were not significant, there was a main effect of beta-Lg genotype on fat concentration, actual milk yield, actual fat yield, 305 d fat yield and lactation period in Brown Swiss and Holstein cows, but not on 305-days milk yield. We suggest that production and percentage of fat ratio may be maximized by the use of beta-Lg AA genotype and milk production by the use of beta-Lg AB genotype with selective goal in herds.