INFLUENCE OF PROLACTIN (PRL) AND BETA-LACTOGLOBULIN (BLG) GENES ON INDICATORS OF DAIRY PERFORMANCE IN COWS OF THE BELARUSIAN BLACK-AND-WHITE BREED

The results of the studies showed that by prolactin gene (PRL), highest yield was found in first-calf heifers with PRLBB genotype 4.7% -10.5% as compared to herd-mates other genotypes; and cows second third lactations – PRLAB 2.6-10.6%. In terms milk fat, animals had a higher rate than PRLAA genotypes 0.04-0.17 pp, especially lactation having most noticeable changes. By beta-lactoglobulin (BLG) gene, BLGAA for 305 days heifers; BLGAB genotype, BLGBB genotype. content butterfat protein milk, on contrary,the rates first calf genotype; second-lactation PRLAB, third-lactation