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Obtaining highly productive animals is possible thanks to the introduction of modern systems for the targeted cultivation of repair young animals. Jersey breed animals are particularly popular among cattle breeders due to their unpretentiousness to the feeding and maintenance system, as well as increased protein and fat content parameters compared to other breeds. The manifestation of individual differences in productive qualities in the cultivation of repair heifers during ontogenesis allows an early determination of the direction of their production use. The study of the relationship between the intensity of growth of young animals with the results of the evaluation of the milk productivity of the first heifers following the results of the first completed lactation showed the presence of a positive relationship (r = 0,96) between these two parameters. Thus, the highest milk productivity is observed in cows, which in the period from 0 to 6 months had an average daily increase in live weight at the level of 811–961 g, which is generally consistent with the research of Russian and foreign authors and opens up new prospects for improving the productive and economically useful characteristics of the Jersey cattle population in the North Caucasus.

Dairy cattle of the red steppe breed are adapted to arid conditions, have high adaptive qualities and are still in demand for breeding in agricultural organizations. The article describes the characteristics of the population of cows of the red steppe breed according to the main indicators of milk quality in the farms of the Stavropol Territory. The mass fraction of fat and protein, the amount of fatty acids in milk, as well as the correlation coefficients between milk indicators and paratypical factors were determined. The research results have shown that milk corresponds to the breed characteristics characteristic of this breed of cows. The average annual dairy productivity of a herd of cows located on the border of the northeastern slope of the Stavropol Upland and the southwestern part of the Manych Lowland (n = 380-430 heads, herd I) is 4.0-4.3 thousand kg/head, and a herd of cows located in the northeastern part of the steppe plain of the Stavropol Territory (n = 600-636, herd II), respectively, the milk productivity is 4.1-4.4 thousand kg / head of milk. The average annual fat content in milk in cows was in the range of 4.08-4.45%, while in cows of the II herd this indicator was higher by 9.5%. The average annual protein content in milk, respectively, was at the level of 3.32-3.63%, while in cows in the II herd this indicator was higher by 9.2%. The percentage ratio of unsaturated to saturated fatty acids was 44,9% in cows in the II herd and 58% in cows in the I stad.

Line breeding is a difficult but effective zootechnical process in purebred sheep husbandry. Linear sheep consistently transmit their characteristics to offspring in order to increase and identify the most promising genotypes, characterized by high productivity and breeding efficiency, by detecting interline selection. The main purpose of the work was to identify the most suitable options for intra- and interline selection of the Russian meat merino breed. The article studies the early development of animals’ growth and physique, the high rates of animals, live weight in different age periods, slaughter and meat qualities. We established that young animals obtained by mating between the animal lines VK-40 and ME-50 were characterized by more proportional body shapes, better slaughter and meat qualities. The increase in live weight of lambs obtained by mating queens of the VK-40 line and rams of the ME-50 line (group III) was more intense than their peers from the intraline selection of the VK-40 line (I group) and of queens of the line AC- 30 with ME-50 rams (group II). The heaviest carcasses were in lambs obtained from the mating of queens of the VK-40 line and rams of the ME-50 line (13.26 kg), the weight of the carcass was greater, compared with the same indicator of the peers of groups I and II, respectively, by 7.7% and 4.0%, by internal fat mass – by 21.8% and 9.8%, by slaughter weight – by 8.3% and 4.3%.

Line breeding is often used in purebred animal husbandry, although the combination of lines may affect undesirable result. Therefore, it is very important for animal breeders to know which lines of animals can be combined to produce highly productive offspring with high meat and wool properties. This article studies the influence of interline selection of Russian meat merino breed on wool productivity, quality and skin histostructure. We found that the highest clipping was in the animals of group III obtained from ME-50 line rams and AS-30 line ewes. Ewes exceeded their peers of group II from the intraline AC-30 selection and peers of group IV from AS-30 line rams and ME-50 line queens. At the same time, ewes of group III insignificantly exceeded peers of group I from intraline selection of ME-50 line animals by 2.0% (P>0.05). Animals of group III had rather high fleece indices in terms of the wool condition due to the influence of ME-50 rams. Moreover, they had the highest ratio of “fat:sweat” (0.84), which confirms the high technological wool properties of this genotype. The quality of sheepskins depends on the nature of the connection of collagen fibers in the reticular layer. In terms of the thickness of the skin reticular layer young ewes of the group III exceeded their peers in groups I, II and IV by 5.3% (P> 0.05), 21.9% ( P