Biochemical and histological indicators of blood and m. longissimus dorsi of young bulls of Kazakh white-headed breed of different genotypes by the CAPN1 and GH genes

The use of molecular genetic markers for productivity is one of the modern approaches in breeding beef cattle. The article presents the results of the studies on the influence of genotypes by the calpain (CAPN1) and growth hormone (GH) genes on live weight, fatty acid composition of blood plasma, quantitative and qualitative indicators of meat of young cattle of Kazakh white-headed breed. It was established that animals of the homozygous geno-types СС–CAPN1 and VV-GH had a larger live weight and its average daily gain on the 240th and 365th days. Their superiority over the GG and LL genotypes was 13.8% (P<0.05) and 6.9%; 14.6% (P<0.05) and 6.9%, respectively. The carriers of the desirable alleles in the homozygous state had the sum of unsaturated fatty acids higher by 6.3% and 7.1%, respectively, than the young bulls, in which genotypes they were absent. The predominance of unsaturated fatty acids over saturated fatty acids also determined lower values of lipid me-tabolism direction index (0.92 and 1.00) in the animals with the desirable genotype. Muscle tissue of animals of the СС and VV genotypes was characterized by a higher level of protein, fat by 0.28–2.13 abs. per cent, energy value, and the quantity of muscle fibers with a smaller diameter per unit area compared to the GG and LL genotypes by on average 8.7% and 25.5% (P<0.01). Due to the greater number of interfiber fat inclusions, muscle tissue of the desirable genotypes received higher marbling scores. The obtained data testify to the prospects of replication of animals, which genotype has the desirable alleles for further improvement of traits of meat productivity of Kazakh white-headed breed.