kappa-casein, beta-lactoglobulin and growth hormone allele frequencies andgenetic distances in Nelore, Gyr, Guzera, Caracu, Charolais, Canchim and Santa Gertrudis cattle

The genotypes for kappa-casein (kappa-CN), beta-lactoglobulin (beta-LG) and growth hormone (GH) were determined by polymerase chain reaction (PCR) and restriction enzyme digestion in seven breeds of cattle (Nelore, Gyr, Guzer a, Caracu, Charolais, Canchim and Santa Gertrudis). kappa-Casein had two al leles with the A allele occurring at a higher frequency in Bos indicus bree ds (0.93, 0.92 and 0.91% for Gyr, Guzera and Nelore, respectively). The bet a-lactoglobulin locus had two alleles in all of the breeds. European breeds had a higher frequency of the beta-LG A allele than Zebu breeds. The GH lo cus had two alleles (L and V) in Bos taurus and was monomorphic (L allele o nly) in ail of the Bos indicus breeds evaluated. The highest frequency for the V allele was observed in Charolais cattle. The markers used revealed a considerable similarity among breeds, with two main groups being discernibl e. One group consisted of Zebu and Santa Gertrudis breeds and the other con sisted of European and Canchim breeds.