The Small Tailed Han is a prolific local sheep breed in China. The bone morphogenetic protein receptor IB (BMPR-IB) gene, which affects the fecundity of Booroola Merino sheep, and the bone morphogenetic protein 15 (BMP-15) gene, which affects the fecundity of Inverdale, Hanna, Belclare, Cambridge, and Lacaune sheep, were studied as candidate genes associated with the prolificacy of Small Tailed Han sheep. Single nucleotide polymorphisms of BMPR-IB and BMP-15 genes were detected in Small Tailed Han ewes (n = 188) by PCR-RFLP. The combined effect of the 2 genes on the prolificacy of Small Tailed Han sheep was studied. The results indicated that the same FecB mutation (Q249R) occurred in the BMPR-IB gene in Small Tailed Han ewes as found in Booroola Merino ewes. The Small Tailed Han ewes with genotypes FecB(B)/FecB(B) and FecB(B)/FecB(+) had 1.40 (P < 0.01) and 1.11 (P < 0.01) more lambs, respectively, than those with genotype FecB(+)/FecB(+). The same FecX(G) mutation (Q239Ter) of the BMP-15 gene was found in Small Tailed Han ewes as in Belclare and Cambridge ewes. The Small Tailed Han ewes with the heterozygous mutant FecX(G)/FecX(+) had 0.55 (P < 0.01) more lambs than those with the wild-type FecX(+)/FecX(+). The Small Tailed Han ewes carrying mutations in both BMPR-IB and BMP-15 genes had greater litter size than those with either mutation alone. In view of our results, marker-assisted selection using both BMPR-IB and BMP-15 genes is warranted to increase litter size in sheep and will be of considerable economic value to sheep producers.

The Jining Grey is a prolific local goat breed in P.R. China. Bone morphogenetic protein 15 (BMP15) gene that controls high fecundity of Inverdale, Hanna, Lacaune, Belclare, Cambridge, and Small Tailed Han ewes was studied as a candidate gene for the prolificacy of Jining Grey goats. According to the sequence of ovine BMP15 gene, six pairs of primers were designed to detect single nucleotide polymorphisms in exon 1 and exon 2 of the BMP15 gene in both high fecundity breed (Jining Grey goats) and low fecundity breeds (Boer, Liaoning Cashmere, and Inner Mongolia Cashmere goats) by single strand conformation polymorphism (SSCP). Two pairs of primers (F1/R1 and F2/R2) were used to amplify the exon 1. Four pairs of primers (F3/R3, F4/R4, F5/R5, and F6/R6) were used to amplify the exon 2. Only the products amplified by primer F5/R5 displayed polymorphism. Results indicated that two genotypes (AA and AB) were detected in prolific Jining Grey goats and only one genotype (AA) was detected in low fecundity goat breeds. In Jining Grey goats frequencies of genotypes AA and AB were 0.10 and 0.90, respectively. Sequencing revealed two point mutations (G963A and G1050C) of BMP15 gene in the AB genotype in comparison to the AA genotype. In Jining Grey goats the heterozygous AB does had 1.13 (p < 0.01) kids more than the homozygous AA does. These results preliminarily showed that the BMP15 gene is either a major gene that influences the prolificacy of Jining Grey goats or a molecular genetic marker in close linkage with such a gene.