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

The aim of the present study was to establish the relationship of LGB genotypes with the traits charac-terizing 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