Association of Polymorphisms in Fecundity Genes of GDF9, BMP15 and BMP15-1B with Litter Size in Iranian Baluchi Sheep

The incidence of mutation in three loci of GDF9, BMP15 and BMP15-1B and their effects on litter sizes was evaluated in Baluchi sheep. Wild-type alleles were detected for BMP15 and BMP15-1B loci and all individuals were found to be as non-carriers for FecB and FecX(G) mutations but, a G to A nucleotide substitution was found in GDF9 locus. The frequency of FecG(+) (0.82) wild type allele was higher than the frequency of FecG(I) (0.18) mutant allele and the frequencies of FecG(+)/FecG(+), FecG(+)/Fecg(I) and Fecg(I)/Fecg(I) genotypes were 0.72, 0.20 and 0.08, respectively in GDF9 locus. The heterozygous (FecG(+)/Fecg(I)) and homozygous (FecG(+)/FecG(+)) non-carrier ewes had 0.35 and 0.21 more lambs than the homozygous (Fecg(I)/Fecg(I)) carrier ewes, respectively (p<0.05). In addition to the finding of segregation of non-additive gene effect on litter size in the previous study in Baluchi sheep, these findings for the first time shows that the Fecg(I) gene has a major effect on litter size in this breed.