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Aim. Polymorphism is the result of evolutionary processes and is inherited, associated with biodiversity and modified by natural selection and functions to preserve various forms of population. It is economically advantageous to find genes that can be used in breeding in such a way as to increase the fertility of animals in different natural geographical zones, since the adaptive abilities of organisms are complicated. In this regard, the purpose of this study was to study the genetic potential of sheep of different breeds bred in various ecological and geographical regions of the North Caucasus with pasture-pasture and pasture-stall conditions of sheep breeding.Material and Methods. Genotyping was undertaken of sheep of different breeds contained in various natural and climatic zones of the Republic of Dagestan and the most arid region of Stavropol Territory in the zone of risky agriculture where the climate is sharply continental. Genotyping in the loci of the genes of differential growth factor (GDF9) and bone morphogenetic protein (BMP15) was carried out by PCR-PDRF (polymorphism of the lengths of restriction fragments) by cutting DNA using endonuclease restriction and further analysis of the size of the resulting PCR fragments. The genetic structure of genes has been studied by methods of genetic and statistical analysis of the data obtained.Conclusion. The genetic structure of sheep populations of different breeds bred in the foothills of the Republic of Dagestan and the arid region of Stavropol Territory was studied for the first time. Information obtained on the role of the degree of genetic variability of sheep of different breeds provides data which can contribute to the ecological well-being of herds and the status characterising the signs of multiple birth rates is also determined. This will further improve and significantly accelerate breeding work with livestock, since an important task of further increasing the efficiency of the industry is the reproduction of the herd together with a simultaneous increase in the productivity of animals.

Aim. One of the important tasks in solving the problem of improving the efficiency of sheep breeding is the rational use of fodder lands in the North Caucasus and the South of Russia, a significant part of which is located in different natural and climatic conditions. The complexity of solutions lies in insufficient knowledge of the mechanisms of adaptation of farm animals, in particular sheep, to the ecological and geographical features of these regions. The purpose of this research was to study the genetic polymorphism of genes, the degree of genetic variability and immune status in sheep of different breeds, since genetic polymorphism is a measure of its adaptability and the hematopoietic function of blood is the basis of the life of the organism.Material and Methods. The genetic structure of the GH/Hae III, GDF9/AsplEI genes and immune status, was studied by the methods of genetic‐statistical and immune analysis in sheep of different breeds kept in different climatic zones of Dagestan and the Krasnodar Territory.Results. As a result of DNA genotyping of the studied samples of sheep of different breeds, it was found that polymorphism of GH/HaeIII, GDF9/AsplEI genes is represented by three genotype variants: homozygous GH/HaeIIIАА, GH/HaeIIIВВ; GDF9/AsplEIАА, GDF9/AsplEIGG; heterozygous GH/HaeIIIAB; GDF9/AsplEIAG and two alleles: A and B – of the GH/HaeIII gene; A and G – GDF9/AsplEI gene with different frequency of occurrence, respectively.Conclusion. For the first time, genetic variability has been studied in the context of the immune status of sheep populations of different breeds bred in the foothills of the Republic of Dagestan and Krasnodar Territory. The information obtained about the role of the degree of genetic variability and the immune status of sheep of different breeds is answered in the formation of adaptive‐compensatory mechanisms to specific conditions of the breeding environment. A deeper study of the adaptive characteristics of sheep of different breeds for their further improvement allows the use of molecular genetic and hematological methods.

Aim. To study the polymorphism of the genes calpastatin (CAST), somatotropin (GH) and differential growth factor (GDF9) of sheep of the Dagestan mountain breed.Material and Methods. Studies on the genetic typing of Dagestan mountain sheep according to CAST, GH and GDF9 genes were carried out in conditions of distant pasture farming in the Republic of Dagestan by the Genetics and Breeding Laboratory of the Federal Agrarian Scientific Centre of the Republic of Dagestan, an accredited laboratory of immunogenetics and DNA technologies of the All-Russian Research Institute of Sheep and Goat Breeding and a branch of the North Caucasus Federal Scientific Agrarian Centre. These investigations were undertaken by the PCR-RFLP method (polymyrase chain reaction - restriction fragment length polymorphism) on a Tersik four-channel programmable thermal cycler from DNA-Technologia (Russia) using specific primers synthesized in the SYNTHOL research and production laboratory (Moscow).Results. Carrying out PCR-RFLP revealed breed-specific alleles with different frequency of occurrence, which was: in the locus of the CAST gene - allele CASTN - 0.03; allele CASTM - 0.97; at the GH gene locus - GHA allele - 100.0, GHB allele - 0; in the locus of the GDF9 gene - the GDF9A allele - 0.25, the GDF9G allele - 0.75, which determined the frequency of occurrence of the homo- and heterozygous genotypes: CASTNN, CASTMM and CASTNM - 93.0; 0 and 7.0%; GHAA, GHBB and GHAB - 100.0 and 0%; GDF9AA, GDF9GG and GDF9АG- 16.0, 66.0 and 19.0%, respectively.Conclusion. The regularity revealed can be considered as an ecological factor that optimizes the adaptive functions of the sheep's organism, on the one hand, an evolutionary selection process that contributes to the creation of a specific way of genetic structures in the population, on the other. The assumption is made that the information obtained can serve as the beginning of a more in-depth study of the unique gene pool of sheep of the Dagestan rock breed for its further improvement. Variants of genetic marker profiles of parental pairs are proposed for accumulation in breeding herds bred in different ecological-geographical zones and genotypes of carriers of selection-significant genetic structures.

Aim. The rational use of North Caucasus forage lands, a large part of which is located in the mountains, is one of the important tasks in addressing the issue of improving the efficiency of cattle breeding. This appears quite challenging, as the mechanisms of adaptation of farm animals, in particular cattle, to the environmental and climatic peculiarities of a certain region have not been sufficiently explored. Since hematopoietic function of blood is the basis of organism’s vital functions and genetic polymorphism is the measure of its adaptability, the present study is aimed at examining haematological profile and the degree of genetic variation in the Brown Caucasian cattle.Materials and Methods. Haematological, genetic and statistical methods of analysis were used to examine the haematological profile and genetic structure of genes GH, PIT‐1, PRL in Brown Caucasian dairy cattle, bred in different ecological and climatic zones of Dagestan.Conclusion. This was the first time that hematopoietic function was studied in the context of genetic variation in Brown Caucasian dairy cattle bred in the foothills (100‐200 m above sea level) and mountains (650‐1,250 m above sea level). The information obtained gives an idea of and an answer to the question about the role of haematological profile and the degree of genetic variation in the development of adaptive and compensatory mechanisms to specific environmental conditions. The use of haematological, molecular and genetic methods allows the further exploration of the adaptation traits of Brown Caucasian dairy cattle for their further improvement.

Aim. Widespread iodine deficiency causing endemic diseases in the highlands of the North Caucasus relate to the iodine epidemic. This type of pathology causes economic damage to the livestock industry, including sheep. In this regard, the aim of this work was to study morphobiochemical changes, hormonal (thyroid) background, immune reactivity in Karachai sheep during ontogenesis in different ecological zones with different iodine availability levels as well as to consider the effect of exogenous hormone (thyroxine) on the immune status of young stock under conditions of iodine deficiency and determine promising ways of developing an effective method of prevention and treatment against the pathology.Methods. We conducted an analysis of the blood of lambs aged 1, 2, 3, 4 and 8 months kept in conditions of unequal iodine provision. The serum concentration of thyroid hormones (T3, T4) was evaluated by the results of an enzyme immunoassay, morphobiochemical status and immune reactivity by hematological, biochemical analysis, correction of iodine deficiency by intramuscular injections of thyroxine at a dose of 1 mg/kg with an interval of 2-3 months.Results. The ontogenetic features of the formation of morphobiochemical systems, hormonal background, immune status in sheep kept in different climatic zones with different iodine provision were established.Conclusion. Disorders of hematopoietic function, differences in hematological parameters, hypoproteinemia, changes in hormonal levels, low levels of immunocompetent T and B cells in the blood of sheep from different zones were detected. It was established that the metabolic response to exogenous thyroxine contributed to the normalization of metabolic processes and activation of cellular immunity.

Aim. The widespread use of so‐called commercial breeds leads to the loss of a unique gene pool of native breeds and the narrowing of the genetic base that is necessary to preserve and to increase the genetic diversity of cattle breeds which are still preserved. These breeds include the Caucasian Brown. In connection , the aim of this research was to study the polymorphism of PIT‐1, PRL and GH genes in dairy cattle bred in different ecological climatic zones of the Republic of Dagestan to identify the genotypes of carriers of selection‐significant marker alleles for their preservation and further use in the selection process.Material and Methods. Genotyping of the Caucasian brown breed cows bred in different natural climatic zones was carried out using PCR‐RFLP methods. The polymorphism of PIT‐1, PRL and GH genes was studied, population analysis of their distribution in the cattle stock studied was carried out and the features of the genetic structure in the researched populations were studied in relation to the conditions of their habitat.Results. The specific allelic PIT‐1, PRL, and GH gene spectrum, characteristic for each animal population studied has been established. Homozygous and heterozygous carrier genotypes of the desired marker alleles with frequency of occurrence depending on both the gene and the animal population were identified. The genetic structural features of the genes studied in the researched populations were revealed.Conclusion. The data obtained indicate the genetic uniqueness of the Caucasian Brown breed bred in different natural climatic zones in the Republic of Dagestan and are probably associated with the manifestation of adaptations, the nature of which has developed under the influence of the prevailing ecological, natural climatic conditions of its habitat.