MILK PROTEIN POLYMORPHISM IN SWISS DAIRY-CATTLE

Individual cow milk samples from (a) 208 original Swiss Simmental (OSS ), (h) 220 of their crosses (Simmental cattle = FV) with American Red Holstein (RH), (c) 215 original Swiss Brown (OSB) and (d) 390 of their crosses (Brown cattle = BV) with American Brown Swiss (BS) were genot yped for the variants of milk caseins (Cn) and beta-Lactoglobulin (bet a-Lg). In addition, the association between kappa-Cn genotypes and mil k yield was studied. Reasonable differences in the allele frequencies were found between the breeds. Compared to pure-bred OSS, crossing wit h RH resulted in a decrease in the frequencies of alpha(s1)-Cn C, beta -Cn B and kappa-Cn B and in an increased frequency of beta-Lg B. Withi n OSB, increased crossing with BS resulted in a decrease in the freque ncies of alpha(s1)-Cn C and beta-Cn B and in increased frequencies of kappa-Cn B and beta-Lg B. A significant association between the kappa- Cn locus and milk yield could only be shown for the OSS breed.