Background and Aim: The market demand for the quality of milk and dairy products, in particular in terms of such indicators as fat content, the amount and composition of milk protein, etc., is growing. Thus, the need for the selection of dairy herds using genetic markers associated with qualitative traits of milk productivity is becoming urgent. This study aimed to determine the preferred and undesirable genotypes of the AluI polymorphism of the growth hormone gene and SnaBI polymorphism of the insulin-like growth factor-1 gene associated with milk productivity and quality indicators of the black-and-white breed. The genotypes of animals were determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Materials and Methods: Samples of the black-and-white breed from Kazakhstan served as the research subjects. The polymorphism of the growth hormone and insulin-like growth factor-1 genes was determined by PCR-RFLP. The relationship of bGH-AluI and bIGF-1-SnaBI polymorphisms with productivity was assessed (fat, protein, and milk yield for 305 days of lactation, live weight, somatic cells, and milk production coefficient) by analysis of variance using Statistica 6.0 software. Results: The black-and-white cows with the bGH-AluILV genotype had significantly higher milk yield in 305 days (3174.5±157.2 kg) than those with the bGH-AluILL (2940.0±152.6 kg) and bGH-AluIVV genotypes (2964.0±36.0; p<0.05). The milk fat content of cows with genotypes bGH-AluILV and bGH-AluILL (121.8±6.5 and 120.6±10.2, respectively) was significantly higher than those with bGH-AluIVV genotype (109.8±10.8; p<0.05). The black-and-white cows with the bGH-AluILV genotype (96.7±5.3) had significantly more milk protein than those with the bGH-AluILL (90.3±5.6) and bGH-AluIVV (86.9±4.6) genotypes (p<0.05). There were no statistically significant differences in the indicators of milk productivity of cows with different genotypes of bIGF-1-SnaBI polymorphism. Conclusion: The results showed that the bGH-AluILV genotype was preferred for the black-and-white breed. The study demonstrated that genotype determined the relevant qualities, while the conditions of feeding, maintenance, and industrial technology provided the manifestation of this genotype. Thus, cows of the same (Wis Burke Ideal) line, having common ancestors in close (IV–V) ranks but living in different farming conditions, had large differences in milk productivity level. The variation was 2046 kg or 67.6% of milk per lactation.

The purpose of the study is to identify paired combinations associated with meat productivity in Aberdeen-Angus cattle for the genes of the somatotropin cascade (growth hormone bGH, growth hormone receptor bGHR, insulin-like growth factor-1 bIGF-1). The determination of animal genotypes was carried out by PCR-RFLP. Results of statistical processing was carried out using the software capabilities of "Microsoft Excel 2010" and "Statistica 6.0". Paired combinations study of bGH, bGHR and bIGF-1 somatotropin cascade revealed marking diplotype polymorphic genes associated with signs of meat productivity and allowing for a comprehensive assessment of the Aberdeen-Angus cattle genetic potential in the postnatal development early stages. Thus, the animals' live weight with the bGH-AluI VV -bIGF-1-SnaBI BB diplotype at the age of 24 months exceeds the Aberdeen-Angus breed live weight standard by 45 kg (12%) and the total sample -by 12.52 kg (3%). The bGH-AluI LL -bIGF-1-SnaBI AA diplotype score is 2.93% higher than the total sample. The mass index average value of animals with the bGH-AluI LV -bGHR-SspI FY diplotype at 18 months is 3.98% lower than the total sample. In animals with the bGHR-SspI FF -bIGF-1-SnaBI BB diplotype at the age of 24 months, the churn index value is lower than the total sample by 3.74%. Thus, the diplotypes bGH-AluI VV -bIGF-1-SnaBI BB and bGH-AluI LL -bIGF-1-SnaBI AA can be considered genetic markers of increased meat productivity and the diplotypes bGH-AluI LV -bGHR-SspI FY and bGHR-SspI FF -bIGF-1-SnaBI BB -reduced meat productivity. The animals' selection with diplotypes that increase meat productivity will reduce the investment period and increase the agricultural production profitability. For breeding activities, it is recommended to maintain the animals' number with the diplotypes bGH-AluI VV -bIGF-1-SnaBI BB and bGH-AluI LL -bIGF-1-SnaBI AA .

Kazakh white-headed and Auliekol breeds are mostly spread through Kazakhstan and are animals with dual purpose productivity directions including meat and milk. Kazakh native cattle breeds are still largely unexplored based on the genetic markers and are of great interest in the country. In this study, we for the first time applied high-density SNP genotyping for two indigenous cattle breeds to study genetic diversity, population structure and relationships with the different foreign breeds. Using of GGP Bovine 150K SNP array the principal component analysis (PCA), populations estimates of the genetic structure (ADMIXTURE), genetic diversity and distances (Fst), and phylogenetic tree showed that the Kazakh white-headed and Auliekol breeds have certain separate genetic structure that differ from European and Russian cattle breeds The two of these Kazakh cattle breeds have their genetic background according to observed results as distinct breeds. The obtained results will be aided in the development breeding system and conservation programs of the Kazakh white-headed and Auliekol breeds of beef cattle in the Kazakhstan.

Technologies for genetic labeling of economically useful traits using polymorphic variants of genes that control the rate of growth and development of animals make it possible to assess the genetic potential of an animal immediately after birth, which significantly reduces time and financial costs. This study aimed to identify paired combinations of the genes growth hormone, growth hormone receptor, and insulin-like growth factor-1 associated with meat productivity in related breeds of cattle meat direction: Hereford, Kazakh white-headed, Aberdeen Angus, Auliekol. The materials for the study were blood and hair follicles samples of animals born in 2015, aged 18 and 24 months. The animals were selected from farms in northern Kazakhstan with equal feeding and housing conditions. The PCR-RFLP method was used to determine the genotypes of animals. According to the results of this study, the associations of phenotypes with the genotypes of the bGH, bGHR, and bIGF-1 genes in the studied cattle breeds were revealed.