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

Abstract

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