Abstract：FecB mutation of bone morphogenetic protein receptor IB gene(BMPR-IB) is the major gene responsible for prolificacy in Booroola Merino and Small Tail Han sheep. In our research, 135 ewes with their two or more litters (totally 353) and 211 sires were selected. FecB mutation was detected by PCR-RFLP and the litter size of ewes with different genotypes were analyzed. The result showed that three genotypes (BB, B+ and ++) were detected in Duolang sheep(Ovis aries). Genotype frequency of BB, B+ and ++ was 0.005, 0.146 and 0.849, respectively. The Duolang ewes with genotype B+ had 0.51 (P<0.01) lambs more than those with genotype ++. No significant difference in ewes with genotype BB and B+ or BB and ++. Chi-square test showed that the Duolang sheep population was in Hardy-Weinberg equilibrium in FecB locus, which indicated that the population could not be affected by selection. It is the first time that BB genotype (one sire and two ewes) in FecB mutation was detected in Duolang sheep which reveals that the mechanism of high prolificacy in Duolang sheep can be the same as Booroola Merino and Small Tail Han sheep. In Duolang sheep industry, FecB mutation detection can be used to breed new strain of mutton and prolificacy.
