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Abstract

The current study investigated the impact of growth hormone (GH) and polymorphism of calpain genes (CAPN1) on the changes in live weight and qualitative and quantitative indicators of meat productivity of young Kazakh White-headed cattle. CAPN1 polymorphism is represented by two alleles, C and G, with a frequency of 0.12 and 0.88, three genotypes, CC, CG, GG, with a frequency of 0.06, 0.81, and 0.13, respectively. GH polymorphism -V and L alleles, with a frequency of 0.40 and 0.60, and VV, LV, and LL genotypes with a frequency of 0.31, 0.51, and 0.18, respectively. The CAPN1 C and GH V alleles are preferred for improving the quantity and quality of meat productivity of the Kazakh white-headed cattle. Animals with the CAPN1 CC and GH VV genotypes had a 6.9% higher body weight at 12 months of age (P<0.05) compared to those with the CAPN1 GG and GH LL genotypes. The highest preslaughter, slaughter, and carcass weights were obtained from carcasses of CAPN1 CC and GH VV homozygous bulls. Their superiority over the CAPN1 GG and GH LL genotypes was 19.3; 16.2 and 16.4 kg; 19.8; 19.1 and 16.1 kg, respectively. The difference in favor of these genotypes in terms of the meat ratio by 4.1% and 2.0% was provided by a 9.1% greater meat mass and 1.4% and 2.0% slaughter yield. The protein and fat content in the longissimus muscle of the CC and VV genotypes carcasses was higher by 0.28-2.13%. CAPN1 CC and GH VV animals had a higher concentration of unsaturated fatty acids in their muscle lipids than CAPN1 CG , CAPN1 GG, and GH LV , GH LL genotypes. The best unsaturated to saturated fatty acids ratio and the ratio of arachidonic (C20:4) and linoleic (C18: 2) acids indicate the advantage in beef's dietary properties obtained from beef CAPN1 CC and GH VV animals.