[Study on BMP15 and GDF9 as candidate genes for prolificacy of Small Tail Han sheep]

Bone morphogenetic protein 15 (BMP15) gene and growth differentiation factor 9 (GDF9) gene which control the fecundity of Belclare and Cambridge ewes were studied as candidate genes on the prolificacy of Small Tail Han sheep. Single nucleotide polymorphism of GDF9 gene and BMP15 gene was detected in both high fecundity sheep breeds (Small Tail Han sheep and Hu sheep) and low fecundity sheep breeds (Dorset sheep, Texel sheep and German Mutton Merino sheep) by PCR-RFLP. The results showed that the G8 mutation (C --> T) of GDF9 gene and the B4 mutation (G --> T) of BMP15 gene were not detected in five sheep breeds. There was the same B2 mutation (C --> T) of BMP15 gene in Small Tail Han sheep as that in Belclare and Cambridge ewes. The same B2 mutation did not exist in other four sheep breeds. Concerning the B2 mutation of BMP15 gene, AA and AB genotypes were detected in Small Tail Han sheep, frequency of A allele was 0. 734, frequency of B allele was 0.266. The BMP15 B2 genotype distributions were high significantly different (P < 0.001) between Small Tail Han sheep and other four sheep breeds. The ewes with heterozygous mutant AB had 0.62 (P < 0.01) lambs more than those with wild homozygous type AA in Small Tail Han sheep. These results indicated that the B2 mutation of BMP15 gene had significant effect on the fecundity of Small Tail Han sheep and ruled out the possibility that the fecundity of Small Tail Han sheep was affected by the G8 mutation of GDF9 gene and the B4 mutation of BMP15 gene.