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Modern sheep breeding should be based on the production of high quality sheep products. Knowing the limits of animal productivity potential allows to manage the breeding process in the most effective way. Applying PCR-RFLP method makes it possible to identify allelic variants of genes associated with quantitative and qualitative characteristics of animals. By identifying different polymorphic variations and their phenotypic manifestations, one can create and replenish a database for managing the genetic progression of breeding-significant traits. The paper determines the gene polymorphism of growth hormone (GH), calpastatin (CAST) and growth differentiation factor (GDF9) of experimental animals and reflects an associative connection between the dynamics of growth and that of development of crossbred one-shear sheep of different origin (Russian meat merino ewes and imported producers). The article concludes that in order to increase sheep meat productivity, farms should give preference to animals carrying genes with the identified desired genotype on the studied polymorphisms and take into account their presence in the breeding process.

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