The growth, development and meat qualities characteristics of different genotypes lambs he growth and development features of three different genotypes ram-lambs, from their birth to six months age, were studied, in particular: purebred youngling of the Ascanian Fine-Fleeced breed (AFF), a cross of this gene pool with the Texel (AFFxT) and Merinolandschaf (AFFxM) breeds. Control over the growth and development these experimental animals was carried out by weighing in different age periods. The meat quality was assessed based on the slaughter results. It was found that the best development parameters were characteristic for the Texel crossbred with the Ascanian Fine-Fleeced breed; therefore, this crossing option has the meat productivity highest genetic potential. Keywords: sheep, genotype, live weight, linear parameters, growth rate.

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For the first time, the genetic structure of sheep breeds (Ascanian Fine-Fleeced, Ascanian Meat-and-Wool, AND Ascanian Karakul) and the hybrid Ascanian Fine-Fleeced × Texel was studied for structural gene variants: growth hormone, calpastatin, myostatin, and Booroola bone morphogenetic protein. In all studied groups, sheep were characterised by polymorphism of two loci, growth hormone and calpastatin. Two genotypes (A/A, A/B) represent genes of growth hormone structure, and three (M/M, M/N, N/N) represent genes of calpastatin structure. Other genes are in a monomorphic state. Analysis of the genetic relationships between the studied gene pools showed that there was a definite relationship between productivity of sheep herds and their molecular genetic parameters. Thus, the frequencies of individual genotypes and alleles change in the direction from Fine-Fleeced animals to sheep bred for meat productivity. For example, the heterozygous genotype A/B proportion of growth hormone gene increases in this direction from 0% to 38.2%, and allele A from 0.083 to 0.191. The live weight of Fine-Fleeced lambs with geno-type A/B at birth was 4.5 kg, and with homozygous genotype A/A — 4.9 kg (p < 0.001). This difference is genetically related to the meat productivity of sheep. A similar relationship was established for young Ascanian Karakul sheep. According to the distribution of polymorphic loci variants, the gene pools of Ascanian Meat-and-Wool breed and cross-bred animals are most similar closest among themselves, which is explained by the same direction of their productivity. At the same time, all populations are in genetic equilibrium according to Hardy-Weinberg equations, which indicates a high level of their consolidation. Sheep, which have the A/A homozygote of the gene growth hormone, have increased body weight.

Aim. To determine the level of polymorphism of some genes, pertaining to the quantitative traits of sheep and to study the genetic diversity and population structure of breeds of Askanian sheep and one of its hybrids. Methods. Molecular–genetic, population–statistical, biometric methods. Results. The genetic structure of populations of the Askanian Fine-Fleeced (AFF, n = 33), Askanian Meat-and-Wool (AMW, n = 22) and Askanian Karakul (AK, n = 46) breeds and a hybrid of Askanian Fine-Fleeced × Texel (AFFT, n = 40) has been studied for the fi rst time in terms of the polymorphisms of the following qualitative trait genes (loci) : meat productivity genes: ovine growth hormone (GH), calpastatin (CAST) and myostatin (MSTN); prolifi cacy genes: Booroola (fecundity gene FecB) and bone morphogenetic protein (BMP15). The sheep in all studied breeds and the hybrid mentioned above are characterized by the polymorphism of two loci, GH and CAST. The other three loci studied did not show polymorphism for the markers studied. GH is present as two genotypes (A/A, A/B), and CAST as three genotypes (A/A, A/B, B/B). The remaining genes were found to be in the monomorphic state. The frequencies of certain genotypes and alleles change in the direction from fi ne–fl eeced to meat animals. For instance, the concentration of heterozygous growth hormone (GH) genotype A/B increases from 0.0 % (AFFB) to 38.2 % (AMWB), and the concentration of allele A – from 0.083 to 0.191. The live bodyweight of fi ne–fl eeced lambs with GH genotype A/B at birth equaled 4.5 kg, and those with homozygous genotype A/A – 4.9 kg (P < 0.001). Therefore, homozygous genotype А/А determined the increased level of meat productivity of sheep. A similar dependence was established at birth for the Askanian Karakul breed. Conclusions. The specifi city of genetic structure of Askanian breeds and hybrid is polymorphism of the GH and CAST and absence of polymorphism of BMP15 and FecB genes, determining the prolifi cacy (reproduction) trait. According to the distribution of polymorphic loci variants, the gene pools of Askanian Meat-and-Wool breed and the local Askanian-Texel hybrid are closely related and therefore explains the same direction of their productivity. At the same time, all populations are in a state of genetic equilibrium according to Hardy-Weinberg, which indicates a high level of their consolidation. Sheep which have the A/A homozygote of the gene growth hormone are characterized by an increased level of the body weight development.