Genetic markers of meat productivity of the Romanov sheep breed: IGFBP-3, GHo и CAST

Relevance and methods . For molecular genetic analysis, samples taken from Romanov sheep in micro-populations of the Yaroslavl region from the ear by pluck were isolated. Polymorphism of genes of the type 3 protein that inhibits insulin-like growth factor (IGFBP-3), growth hormone (Gh), and calpastatin (CAST) in micro-populations of Romanov sheep of the Yaroslavl region was studied. A selection and genetic assessment of live weight indicators of sheep by age periods, depending on the genotype, was carried out. Results . Two variants of IGFBP-3 gene polymorphism were identified: homozygote (FF) and heterozygote (FG). The frequency of F and G alleles was 94% and 6%, respectively No animals carrying the gg genotype were identified in the study population. Evaluation of gene polymorphism in the population GHo Romanov sheep showed the presence of three genotypes AA, AB and BB with frequency of allele A and b — 63% and 37%, respectively. When evaluating the CAST gene polymorphism, 3 MM, MN, and NN genotypes were identified with different frequency of occurrence. The ratio of M and N alleles in the population was 74% and 26%, respectively. Indicators of observed (Ho) and expected (He) heterozygosity for the studied genotypes are in the range of 0.11...0.62 and 0.10...0.47, respectively. It was found that animals with the IGFBP-3FG genotype had a significantly higher live weight at the age of 10 months compared to carriers of the IGFBP-3FF genotype by 5.7%. For the GHo gene, the greatest significant superiority in live weight in all the studied age periods was found in individuals with the GHoAB genotype, which ranged from 0.5% to 12.9%. Animals with the CASTMM genotype outperformed animals with the CASTMN and CASTNN genotypes at 5 months of age by 5.61% and 14.8% and at 10 months of age by 4.53% and 11.3%, respectively. The conducted research will speed up the selection process and increase the profitability of the industry.