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The gene pool improvement of North Caucasian population is carried out through artificial insemination of herds with sperm from sires carrying the desired alleles of genes associated with meat productivity and beef quality. The frequency of homozygotes in CAPN1 gene was found in Stavropol population of Hereford sires: CC – 6 %, GG – 88 % and more. This indicator was 50.0 % in the LL genotype of somatotropin gene (GH), which is 22-28 % more than that in hetero and homozygotes LV and VV. The frequency of CC genotype was 61 % higher in TG5 DNA-marker than that of the heterozygous CT form. The use of modern biotechnological methods of herd reproduction made it possible to reduce the degree of homozygosity in CAPN1 and TG5 genes by 28.8% and by 18.1% in the next generation. The homozygosity degree in CAPN1 and TG5 genes were less by 28.8 % and 18.1 % in progeny than that in sires. However, the number of effective alleles was higher by 0.53 % and 0.41 % for CAPN1 and TG5 SNP markers in progeny bulls. The observed heterozygosity varied in the range of 0.281-0.344 for gene markers CAPN1, GH and TG5 in the sire group. A high genetic similarity was established between sires and progeny – an average of 0.973. This indicator was 0.999 and 0.970 for GH and TG5 gene-markers. The largest genetic distance was determined in CAPN1 gene – 0.044. Thus, the high plasticity of the gene pool in North Caucasian Herefords population has been proved under the influence of a targeted mating system of parental pairs based on the improvement of herd reproduction biotechnology. The progeny bulls from sires-carriers of the desired alleles had an advantage over peers in growth rate at the age of 3-7 months and 12-15 months, it amounted to 163.9 g (17.7 %; P

The successful development of sheep farming in the meat sector is largely determined by the use of molecular genetic methods and modern genotypes. The Altai Mountain breed of sheep optimally combines high wool and meat with unsurpassed adaptability to grazing in the highlands of the Altai Republic throughout the year. The genes of calpastatin (CAST) and differential growth factor (GDF9) are considered as promising markers of quantitative and qualitative signs of sheep meat productivity. It was established that in the Altai Mountain breed the polymorphism of the CAST and GDF9 genes is represented by three genotypes MM, MN, and NN; AA, AG and GG with a frequency of occurrence of 0.23; 0.72 and 0.05; 0.10; 0.35 and 0.55, respectively. The level of homozygosity (Ca) in the CAST gene was 73.1%, GDF9 – 60.6%. The level of effective alleles (Na) was higher in the GDF9 gene (1.65) compared with CAST (1.44). The level of factual (Ho) and theoretical (He) expected heterozygosity for the GDF9 gene was 0.538 and 0.651, respectively, for the CAST gene – 0.290 and 0.368, which indicates a certain lack of heterozygotes in both genes. The analysis of slaughter qualities established the superiority of carriers of the NN genotype over the MM genotype in the CAS gene in terms of pre-slaughter and carcass weight, meat ratio by 4.96 and 2.83 kg, respectively (P

The aim of the study was to assess the genetic potential in Canadian Hereford sires using DNA markers, identify complex genotypes and assess their impact on the growth, development and meat productivity of its offspring. Groups of sons were formed taking into account the complex genotypes of sires: group 1 (n = 28) – sons of bulls carrying in their genome a complex of genotypes with desired alleles; group 2 (n = 30) – sons of bulls with a complex of genotypes that lack the desired alleles. The offspring from bulls-carriers of the “desirable” alleles in complex CAPN1, GH, Lep, TG5 genes that meet the exterior requirements exceeded their peers in live weight (P < 0.05), carcass weight (P < 0.05) and muscle tissue (P < 0.05). The maximum conversion rate of feed protein into product protein was also established in the group of sons from selected bulls. Thus, animal selection for body conformation type is advisable to combine with the herd genotyping for a complex of genotypes associated with different economically useful traits when creating highly efficient population of beef cattle.

The results of genotyping of beef cattle (bull-calves of white-faced and Kazakh whiteheaded cattle) made it possible to establish the features of gene polymorphism ensuring meat efficiency (CAPN1, GH, TG5, LEP). Genotype carriers of selection significant alleles marking high efficiency and quality of beef are revealed. Superiority by body weight, daily average gains of homozygous (CAPN1CC GHLL TG5TT LEPTT) genotypes in comparison with alternative (CAPN1GG GHVV TG5CC LEPCC) genotypes was established in the selection of white-faced bull-calves by 13.2 and 14.9%, Kazakh white-headed – by 11.8 and 13.3%. The fatty acid composition of blood lipids of young white-faced, Kazakh white-headed cattle of different genotypes is defined. The features of fatty acid composition of blood lipids depending on pedigree and genotype of animals expressed by integrated indicators characterizing the intensity of biosynthesis of fatty acids are established: index of lipid saturation (ILS), index of lipid exchange intensity (ILEI), metabolism efficiency ratio of essential fatty acids (MER). The determined stable correlation of integrated indicators of lipid exchange intensity with body weight and daily average gains gives grounds for their use as biochemical test systems during lifetime assessment of young cattle breeding potential.