INFLUENCE OF POLYMORPHISM OF THE DGAT1, GH, PRL AND BLG GENES ON MILK PRODUCTIVITY INDICATORS IN COWS OF THE RED BELARUSIAN BREED GROUP

The results of studies on the influence of polymorphism of the genes diacylglycerol O-acyl transferase 1 (DGAT1) and somatotropin (GH) on the milk productivity of cows of the red Belarusian breed group showed that in most cases homozygous animals with the GHLL genotype were superior to their hetero- and homozygous peers with the genotypes GHLV and GHLL in terms of milk yield over 305 days of lactation by 0.9% ... 10.1% (P<0.01), fat and protein content by 0.2 … 0.3 p.p. (P<0.05), the amount of milk fat and protein in milk by 1.1% ... 9.1% (P<0.01). Assessment of milk productivity indicators of cows using the DGAT1 gene in dynamics indicates that with an increase in the serial number of lactation, milk productivity indicators increase: milk yield by 3.8% ... 5.4% (P<0.05), mass fraction of protein in milk – by 0.2 p.p. … 0.3 p.p. (P<0.05), the amount of milk fat – by 4.8% ... 10.6% (P<0.01), the amount of milk protein – by 10.0% ... 19.9% (P<0.01). For the prolactin gene (PRL), the highest milk yield was in heterozygous first-calf heifers with the PRLAB genotype; it exceeded the milk yield of homozygous animals with the PRLAA genotype by 2.5%, and in cows of the second and third lactations, the highest milk yield was in homozygous animals with genotype PRLAA. It was higher than the milk yield of heterozygous cows with the PRLAB genotype in the second and third lactations by 0.8% ... 7.0% (P<0.05), respectively. In terms of fat content and milk protein content, the heterozygous PRLAB genotypes were superior to their homozygous peer animals of the PRLAA genotype by 0.1 … 0.2 p.p. According to the beta-lactoglobulin (BLG) gene, homozygous animals with the BLGBB genotype had a higher milk yield for 305 days of lactation, as well as the amount of milk fat and protein in milk; they exceeded the indicators of hetero- and homozygous peers with the BLGAB and BLGAA genotypes: in milk yield by 0.5% ... 12.7% (P<0.01), in terms of the amount of milk fat – by 2.1% ... 14.4% (P<0.01), and in terms of the amount of milk protein in milk – by 5,9% (P<0.05) ... 9.8% (P<0.01), respectively, and with an increase in the serial number of lactation, the difference in these indicators with hetero- and homozygous peers of the BLGAB and BLGAA genotypes increased.