Polymorphism of CAST, GH, GDF9 genes of Gorno-Altai sheep breed

The results of studying the genetic diversity of local breeds of farm animals are presented. The object of research is the Gorno-Altai mutton-wool breed of sheep, maximally adapted to the harsh climatic conditions of the Altai mountains, and year-round pasture use. The breed is rich in milk, which ensures high survival rate of young animals. The genes and their polymorphic variants associated with breeding traits of sheep were studied. The genes of Calpastatin ( CAST ), Somatotropin ( GH ), and differential growth factor ( GDF9 ) are considered as promising genes marking qualitative and quantitative traits of meat productivity in sheep. The analysis of the DNA diagnostics results revealed that the polymorphism of the CAST , GH , GDF9 genes is represented by two alleles, M and N; A and B; A and G, respectively, and three genotypes – MM, NN, MN; AA, BB, AB; AA, GG, AG with different frequency of occurrence. The frequency of the desired N allele of the CAST gene was 27.5%, the B allele of the GH gene 37.5%, and the A allele of the GDF9 gene 45.0%. A comparative analysis of the level of actual and theoretical expected heterozygosity indicates the ambiguity of the nature of their distribution depending on the gene. The highest indicators of actual and expected heterozygosity were characteristic of the GDF9 gene, which amounted to 0.538 and 0.651, respectively, against 0.290 and 0.368; 0.290 and 0.445 for the CAST and GH genes. The highest (36.9%) degree of genetic variation (V) was characteristic of the GDF9 gene at 24.4%, and 28.3% for the CAST and GH genes. The variability of the heterozygosity test changeability in the studied genes was noted to be not significant: from minus 0.08 for the CAST gene to minus 0.15 and minus 0.11 for the GH and GDF9 genes, which indicates a certain lack of heterozygotes. The research results showed the prospect of including testing, selection and assortment of the studied genes into breeding programs for improving the Gorno-Altai breed of sheep.