Exploring the distribution of polymorphism across diverse breeds Worldwide in the bovine <i>NR5A2</i> gene and its correlation with number of mature follicles and corpus albicans

The <i>Nuclear receptor subfamily 5 group A member 2</i> (<i>NR5A2</i>) gene plays a pivotal role in ovarian development, ovulation, and reproductive traits. There is a lack of studies on its impact on ovarian traits and reproductive traits in cattle. This study aimed to explore <i>NR5A2</i> gene polymorphisms associations with reproductive traits and investigate the distribution of <i>NR5A2</i> gene polymorphisms across diverse bovine breeds worldwide. We identified a novel 17-bp deletion within the <i>NR5A2</i> gene specifically in Chinese Holstein cows (n = 1033) leading to the observation of two genotypes DD and ID. Subsequent association analysis revealed a significant correlation between the 'ID' genotype at this locus and a larger number of corpus albicans (<i>p</i> = 0.042) in diestrus, as well as a higher number of mature follicles (<i>p</i> = 0.038) in estrus. In addition, we also found that the distribution of this deletion exhibits strong regionality across different cattle breeds globally. These findings indicate that the 17-bp deletion mutation within the <i>NR5A2</i> gene is significantly associated with an increased corpus luteum diameter and a greater number of mature follicles, suggesting its potential utility as a valuable DNA marker for enhancing cow fertility.