Whole genome sequencing identified candidate genes related to litter size of Qinghai fine wool sheep under artificial selection

Qinghai fine-wool sheep is a Chinese domestic sheep breed developed by complex crossing. We established a stable genetic core population of twin lambs through artificial intervention. However, few studies have been done on the genetic fecundity of breeding varieties, probably because of the long-term nature and complexity of the work. Selection signatures associated with reproductive traits were identified by whole-genome sequencing of ewes with stable litter size differences to select candidate genes related to the increase in litter size in this breed. Several genes associated with reproductive traits were found through genome annotation, such as pros-taglandin E1 receptor (PTGER1), Growth hormone receptor (GHR), and fibroblast growth factor 9 (FGF9) with significant enrichment in the phosphatidylinositol-3-kinase/Akt (Pi3k-Akt) and Ras signaling pathways, and neuroactive ligand-receptor interaction, suggesting that these pathways may affect fertility regulation. Notably, one synonymous mutation (g. 33661895 T > C) specific to the high-prolificacy group was identified in the GHR gene. In summary, this study provides a new opportunity to improve sheep fertility and provides a scientific scheme for the establishment of a productive core group.