Polymorphism of the gene GDF9 in sheep of Prikatun type of Altai Mountains breedand its correlation with indices of meat rate productivity

In recent decades in many countries of the world the development of sheep farming is determined by the efficiency of mutton production. One of the promising areas of selection improvement of sheep breeds of meat and meat & wool productivity is an application of molecular-genetic methods. To obtain high-quality mutton it is advisable to use the Altai Mountains sheep breed, which features by high energy of growth of young animals and their adaptability to all-year-round pasture management. One of the candidate genes responsible for sheep meat productivity is the gene of growth differentiation factor -GDF9 (growth differentia­tion factor 9). The article presents the results of research of polymorphism of the gene GDF9 and its relation with the parameters of meat productivity in young sheep of Altai Mountains breed. It was found that the rams-carriers of AA genotype outperformed their peers of AG and GG genotypes in terms of pre-slaughter weight, carcass weight, meat yield and meat content ratio by 1.62 and 7.01 kg, 1.34 and 3.98 kg (P<0.05), 1.21 and 1.86 abs. percent, 0.16 and 0.39 units (P<0.05) accordingly. The muscle tissue of rams of the desired genotype featured the highest content of protein, fat and, accordingly, energy value in comparison with AG and GG genotypes. The animals of AA genotype had the largest area of a rib eye and diameter of muscle fibers. The superiority over other genotypes achieved 1.55 cm2 and 1.98 microns in average. In addition the higher number of inter-fiber and inter-bundle inclusions of fat and lower content of connective tissue stipulated higher marbling score (MB)-higher by 3.32 points. The obtained data in­dicate that it is promising methods to increase the number of homozygotic animals in term of gene GDF9 by intended selection of parent animals whose genotype contains a desirable element for further improvement of quantitative and qualitative parameters of meat rate productivity in sheep of Altai Mountains breed.