Influence of genes on growth and development of the studied population of crossbreed sheep

The research object are the genes: CAST (specific inhibitor of calpain), GH (growth hormone gene) and GDF9 (expressed in oocytes and necessary for ovarian folliculogenesis). The research subject is the genetic structure of second­generation crossbreeds of small ruminants. The aim of the research is to study genetic polymorphism in crossbreeds of small ruminants. The scientific novelty consisted in the study of allelic variants of genes through genotyping of crossbred rams of the F2 generation in the conditions of the Republic of Dagestan. The following has been used for the research: gel electrophoresis method; PCR­RFLP method – for the purpose of genotyping the studied sample by the GH, GDF9 and CAST genes. Genetic and statistical analysis was carried out using a standard set of formulas. Polymorphism of the CAST gene was represented by the M allele with a high (0.9) and the N allele with a low (0.1) frequency occurrence. Homozygous genotypes CASTMM and CASTNN, as well as heterozygous CASTMN were distributed in the following ratio: 86.6; 6.7; 6.7 % respectively. The peculiarity of the allelic spectrum of the GH gene, represented by two alleles and two genotypes – GHA and GHB, GHAA and GHAB, was expressed in a lower frequency of occurrence of the GHA allele of GHAA genotype, which amounted to 0.8 and 80 %, respectively. In the studied sample, when studying the polymorphism of the GDF9 gene locus, it has been determined that the frequency of occurrence of GDF9G allele was 1.7 times higher than the frequency of occurrence of GDF9A allele (0.37). As a result of the research, polymorphism of genes with different frequencies of occurrence was established. Analysis of the structure of the studied genes revealed significant genotypes in terms of breeding for targeted selection. In the sample of the studied se condgeneration crossbred cattle, the significant genotypes in terms of breeding are CASTNN, GHBB, GDF9AA.