GENE AND GENOTYPIC FREQUENCIES OF β-CASEIN VARIANTS A1 AND A2 IN DAIRY CATTLE

Abstract

Taking into account the possible benefits that milk containing only β-casein A2 can bring to the intestinal health of individuals and milk constituents, the objective of this work was to identify the allelic and genotypic frequency of variants A1 and A2 of the β-casein gene and their influence on the physicochemical composition of milk from crossbred cows. To identify the genetic profile, tail hairs were collected from 51 crossbred cows for DNA extraction and genotyping, and the gene and genotypic frequencies of the A1 and A2 variants of beta-casein were calculated. The genotypes were associated with the following milk characteristics: fat, total protein, lactose, casein, total solids and defatted dry extract, density and pH. The data from the physicochemical analysis were submitted to the t-test with Bonferroni correction at 5% significance (P<0.05). The content of total solids (12.42 and 15.31%) and fat (2.14 and 4.05%) were different between genotypes A1A2 and A2A2, respectively (P<0.05). The herd is in Hardy-Weinberg equilibrium.