GDF9 gene polymorphism and its association with litter size in two Russian sheep breeds

Abstract

The purpose of this work was to study the GDF9 gene polymorphism in two sheep breeds raised in Russia and to identify its association with litter size. A variety of allelic variants of the GDF9 gene (GDF9/G1 and GDF9/G4 sites) in Salsk and Volgograd sheep breeds was studied. Mutations of the GDF9 gene that lead to improvement of reproductive traits in these sheep breeds were revealed. The obtained results of the alleles and genotypes frequencies for the GDF9 gene showed a low level of polymorphism at G1 and G4 sites. The studied populations were found to have high frequencies of G allele and GG genotype at G1 site and of A allele and AA genotype at G4 site of the GDF9 gene. Herewith all the individuals heterozygous at G1 site were also heterozygous at G4 site. Homozygous AA (G1) and GG (G4) genotypes in the study population were not observed. In the Salsk sheep population the individuals with AG genotype at G1 site had the highest fertility. A similar pattern was observed at G4 site. The litter size of Salsk sheep with GG genotype (G1) was 1.13. Among the Volgograd sheep, the individuals with AG genotype were also characterized by the highest fertility; the litter size of the individuals with the GG genotype (G1) was 1.22. A similar pattern was observed at G4 site. The litter size of animals with AG genotype was 1.88 and the AA genotype − 1.22. Thus, the positive and significant relation between the heterozygous AG/GDF9 genotype and litter size of animals has been established.