Abstract
Reproductive performance in sheep plays a crucial role in determining the economic efficiency of the industry, with increasing litter size being a key focus for genetic improvement. The BMP15 gene is widely recognized as a major gene influencing sheep fertility. In this study, specific mutations in the BMP15 gene of Gobi short tail sheep were identified through direct sequencing, and these mutations were genotyped using the MassARRAY system. The g.54285159_54285161TTA indel was significantly associated with litter size in Gobi short tail sheep (p < 0.05). Three mutations, including g.54291460G>A, g.54288671C>T, and the g.54285159_54285161TTA indel, were significantly associated with litter size in Ujimqin sheep (p < 0.05). Furthermore, the promoter activity analysis demonstrated that the A allele exhibited significantly higher promoter activity compared to the G allele of the g.54291460G>A mutation. These findings highlight valuable genetic markers for improving sheep litter size and provide a robust theoretical foundation for further research on the BMP15 gene's role in reproduction.