Bone morphogenetic protein receptor IB as a candidate gene for prolificacy in Small Tail Han and Hu ewes

AbstractThe bone morphogenetic protein receptor IB (BMPR-IB) gene, which controls the fecundity of Booroola Merino ewes, was studied as a candidate gene for the prolificacy of Small Tail Han and Hu ewes. A single nucleotide polymorphism of the BMPR-IB gene was detected in both high (Small Tail Han and Hu) and low (Suffolk and Dorset) fecundity sheep breeds by polymerase chain reaction–single-strand conformation polymorphism (PCR-SSCP) analysis. The results indicated the presence of the same mutation (A746G) of the BMPR-IB gene in both Small Tail Han and Hu ewes and in Booroola Merino ewes, but not in both Suffolk and Dorset ewes. In Small Tail Han ewes, frequencies of BB, B+ and ++ genotypes were 0.524, 0.383 and 0.093, respectively. In Hu ewes, these frequencies were 0.882, 0.118 and 0.000. The BMPR-IB genotype distributions were significantly different (P<0.001) among high- and low-fecundity sheep breeds. Small Tail Han ewes with genotype BB had 0.92 (P<0.01) and 1.02 (P<0.01) lambs more than those with genotype ++ in the first and second parity, respectively. These results demonstrated that the BMPR-IB gene is a major gene affecting the prolificacy in both Small Tail Han and Hu ewes, and could be used as a molecular genetic marker to select the litter size in sheep.