Genetic diversity and population structure of breeds of Askanian sheep by analysing polymorphisms in qualitative trait loci

Aim. To determine the level of polymorphism of some genes, pertaining to the quantitative traits of sheepand 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 structureof 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) hasbeen 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 thehybrid mentioned above are characterized by the polymorphism of two loci, GH and CAST. The other three loci studieddid not show polymorphism for the markers studied. GH is present as two genotypes (A/A, A/B), and CAST asthree genotypes (A/A, A/B, B/B). The remaining genes were found to be in the monomorphic state. The frequenciesof certain genotypes and alleles change in the direction from fi ne–fl eeced to meat animals. For instance, the concentrationof heterozygous growth hormone (GH) genotype A/B increases from 0.0 % (AFFB) to 38.2 % (AMWB), andthe concentration of allele A – from 0.083 to 0.191. The live bodyweight of fi ne–fl eeced lambs with GH genotypeA/B at birth equaled 4.5 kg, and those with homozygous genotype A/A – 4.9 kg (P < 0.001). Therefore, homozygousgenotype А/А determined the increased level of meat productivity of sheep. A similar dependence was establishedat birth for the Askanian Karakul breed. Conclusions. The specifi city of genetic structure of Askanian breeds andhybrid is polymorphism of the GH and CAST and absence of polymorphism of BMP15 and FecB genes, determiningthe prolifi cacy (reproduction) trait. According to the distribution of polymorphic loci variants, the gene pools ofAskanian Meat-and-Wool breed and the local Askanian-Texel hybrid are closely related and therefore explains thesame direction of their productivity. At the same time, all populations are in a state of genetic equilibrium accordingto Hardy-Weinberg, which indicates a high level of their consolidation. Sheep which have the A/A homozygote of thegene growth hormone are characterized by an increased level of the body weight development.