ASSOCIATION OF BETA-LACTOGLOBULIN (LGB) GENOTYPES WITH QUALITY COMPOSITION OF MILK AND COAGULATION PROPERTIES IN BULGARIAN BLACK-AND-WHITE CATTLE

Abstract

The aim of the present study was to establish the relationship of LGB genotypes with the traits characterizing the qualitative composition of milk and its coagulation ability in cows of the BBW cattle. Milk proteins’ polymorphism was evaluation in 132 tissue samples from cows reared at 4 farms by PCR–RFLP analysis. During the study, the following parameters were studied: daily milk yield (kg), fat and protein contents (%), rennet coagulation time, curd firmness and curd firming time. The presence of 2 alleles of LGB – A, B, which determine three genotypes – AA, AB, BB. Homozygous animals carrying the BB genotype of LGB are characterized by the highest average daily milk yield – 31.00 kg. It was found that animals with genotype AA produce milk with the highest fat content – 3.90%, the fastest rennet coagulation time – 19.82 min and the hardest coagulum – 25.99 mm.