In this study, we used mitochondrial (mt) DNA to reveal patterns of genetic diversity among six breeds of sheep native to Kazakhstan, including the Chu and Kalchengel types of Kazakh mutton-semifine-wool breed of sheep, Akzhayik, Edilbay, Kazakh fat-rumped semi-course-wool and South Kazakh Merino breeds. Mitochondrial DNA D-loop was studied in 64 samples to determine the genetic diversity of the local sheep breeds. The analysis identified 54 haplotypes and 113 polymorphic loci of mtDNA D-loop. For the studied breeds, haplotype diversity and nucleotide diversity were 0.993±0.005 and 0.039±0.001, respectively. The results indicated higher level of nucleotide diversity in the South Kazakh Merino (SKM) breed (0.047), while the lowest diversity was observed in the Edilbay breed (0.029). In addition, the average number of nucleotide differences (Kxy) and the average number of nucleotide substitutions (Dxy) were determined among the studied breeds. The minimal value of genetic distance was observed between Akzhayik mutton-wool and Kazakh fat-rumped semicourse-wool breeds (Kxy: 16.956 and Dxy: 0.039), while the maximum value was observed between the Edilbay and SKM breeds (Kxy: 24.600 and Dxy: 0.040). Phylogenetic analysis revealed the presence of three haplogroups, namely, A, B and C in the collected sample, while the haplogroups D and E were not found. The results indicated that 28 of 64 tested animals belong to haplogroup A (43.75%), whereas 25 of investigated animals were attributed to haplogroup B (39.06%) and 11 animals to haplogroup C (17.19%).

The article presents the results of a study on the effect of top dressing and feed additives based on humic substances on milk productivity, the quality of milk of sheep of the Kazakh fat-tailed semi-coarse breed, and the resulting cheese in pasture conditions. In total, 90 heads of sheep of the Kazakh short-tailed semi-rough-haired breed were used in the experiment. The Control Group (CG) of 30 sheep grazed on pasture grass, while two Experimental Groups (EG) of 60 heads were fed 300 g barley per day of barley, The second experimental group of sheep received a feed additive based on humic substances. As a result, after the first month of feeding, additional feeding had a positive effect on the daily milk yield of ewes, where the experimental group II was statistically significantly superior (P<0.05), i.e., it exceeded by 0.08 liters. In total, during lactation, the sheep of the second experimental group exceeded the control group by an average of 10.8% in average daily milk yield. Also, additional feeding affected the quality of milk and cheese, Thus, the indicators of sheep of the II experimental group were superior in terms of the fat content of milk (P<0.01) and cheese (P<0.05).

The paper analyzes the milk production of Holstein breed of cattle imported from Canada to Kazakhstan. It is found that milk production of Holstein heifers in Northern Kazakhstan conditions is in high enough amounts: milk yield for 305 days of lactation of Canadian heifers is 6,627 kg and for the animals of own reproduction is 6,488 kg. However, the acclimatization of Holstein cows is satisfactory, and they concede to the local animals of black-motley breed on reproductive qualities, especially on the duration of the service period. This is also evidenced by the birth of calves per 100 cows, which was 96.5% for black-and-white cattle, whereas this figure was 76.5% for imported Holstein cows, and it's increased to 78.8% for Holstein cows bred in the conditions of Northern Kazakhstan.

In recent years, the world demand for a low fat and high protein content lean meat had increased to meet the needs of the organism in proteins. This article presents the results of an expedient scientific-research analysis on establishing the influence of Poll Dorset and Texel breed on the particular growth variability, development of both meat and wool productivity of Kazakh mutton-semifine-wool breed of sheep. Results of the study were obtained under the same grazing conditions of 110 head of purebred and 110 crossbreed Texel and Poll-Dorset sheep of second generation. It was found that peers of the experimental group exceeded their peers in the control group on the dynamics of growth in body weight (P£0.05), i.e. crossing helped to improve the performance of daily gain (P£0.05). In terms of slaughter indicators, such as the slaughter and carcass weight, crossbreed male lambs also surpassed purebred male lambs (P£0.05). Herein, it was found that crossbreed lambs of Texel breed observe the superiority in terms of meat output (fat free) in relation to purebred male lambs (P£0.01). The study of longissimus muscle chemical composition showed that crossbreed male lambs of Texel breed in protein content in this very muscle are superior to purebred peers (P£0.05). A study of wool characteristics of experimental sheep showed that at the age of 12 months the high wool clip was observed in male lambs of Texel second generation (P£0.05). The high yield of washed wool was also observed in Texel male lambs (P£0.05) as compared to purebred peers.

Kazakhstan is characterized by a wide variety of natural, climatic, economic, and ethnic factors that have a specific impact on the development of sheep farming. The production of dairy products from sheep is limited due to the low productivity of animals and the seasonality of milk production throughout the year, as well as the short lactation period. Also, one of the problems is manual milking of sheep, which does not allow obtaining sheep milk on an industrial scale. The market of dairy products, currently in the Republic of Kazakhstan is represented only by-products made from cow's milk, and at the same time, most of them are products made from cow's milk powder, so the development of products made from sheep's milk is an urgent task. In addition, sheep's milk is a national product, and one of the tasks is to revive the traditional products of the Kazakh people. The analysis of literature studies shows that in-depth studies of the chemical composition of sheep's milk have not been conducted in Kazakhstan. The chemical composition data obtained during the Soviet period only give an idea of the primary chemical parameters obtained by generally accepted basic methods and do not provide reliable information about the deep chemical composition of the milk of local ewes. According to the results of studies, the content of the essential amino acid valine in cow's milk (0.21 g/100g) is also lower than in sheep's milk (9.69-3.79 g/100g). Sheep's milk protein is digested in the human body by 99.1%, and cow's milk protein by 91.9%. According to world experts, one of the advantages of Kazakhstan's domestic milk products is its naturalness, a low share of the use of genetically modified organisms, and environmentally friendly pastures, due to which they receive high-quality and safe products. Therefore, the designated research topic and its analysis are appropriate and relevant.