Abstract
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.