Whole-genome sequencing to identify candidate genes for litter size and to uncover the variant function in goats (Capra hircus)

To select candidate genes for goat prolificacy, we managed six multi- and six single-kid female goats at the same feeding level and in the same management mode over a 4-year period. These goats showed stable differences in litter size over five continuous parturition records. Whole-genome re-sequencing was used in all 12 to select candidate genes, namely, AURKA, ENDOG, SOX2, RORA, GJA10, RXFP2, CDC25C, and NANOS3, by the strength of their differentiation signals. Most of the selected genes were enriched in the coiled coil process and ovarian development, which suggests that the coiled coil process has a potential regulatory effect on fecundity. Detection of the distribution of variants and association analyses with litter size in 400 goats showed that NANOS3 exon mutations may lead to a transformation of the protein structure. The variation in CDC25C, ENDOG, and NANOS3 showed a significant association with litter size. These results can contribute to the improvement of reproduction traits in the artificial breeding of goats.