GENETIC POLYMORPHISM OF BETA AND KAPPA CASEIN IN CROSSBRED DAIRY CATTLE

Abstract

The objective of this study was to determine the frequencies of the genetic variants of the beta and kappa casein gene in 87 crossbred dairy cattle. Beta and kappa casein genotypes were investigated, the first by an allele-specific polymerase chain reaction (ASPCR) and the second by a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Three beta casein alleles of A1, A2 and B were found, with frequencies of 0.30, 0.61 and 0.09, respectively. In total, five genotypes of A1 A1, A1 A2, A2 A2, A2B and A1B were found, with frequencies of 0.06, 0.41, 0.36, 0.11 and 0.06. Three kappa casein alleles of A, B and E were found, with frequencies of 0.72, 0.26 and 0.02, which constituted five genotypes of AA, AB, AE, BB and BE with frequencies of 0.50, 0.40, 0.03, 0.06 and 0.01. The results showed that the two loci in this herd did not follow Hardy-Weinberg's Law of Equilibrium, with a gametic phase disequilibrium of 0.45 (p<0.05). The results also showed that degrees of polymorphism for beta and kappa casein loci, were 0.50 and 0.58, respectively.