InDel mutations within the bovine <i>PER2</i> gene are significantly associated with reproductive traits

Functioning as a key regulator of circadian rhythms, the <i>PER2</i> gene exerts a substantial impact on the reproductive traits of animals. However, the effect of the <i>PER2</i> gene on ovarian development remains unclear. In order to examine the relationship between bovine reproductive trait and the <i>PER2</i> gene, a total of 901 ovarian samples were collected, categorized into different oestrus cycles (proestrus, oestrus, post-oestrus, anoestrous), and subjected to analysis for two potential insertion/deletions (InDels) in the <i>PER2</i> gene. Through agarose gel electrophoresis and DNA sequencing, two polymorphic deletion mutations (P2-D_5-bp, P3-D_13-bp) were identified. Furthermore, a significant association between mature follicle diameter and P2-D_5-bp was found (<i>P</i> < 0.05). Additionally, several significant correlations with ovarian length, width, height, and white body diameter were found for P3-D_13-bp (<i>P</i> < 0.05). These findings suggested that the bovine <i>PER2</i> gene plays an important role in above-mentioned reproductive traits, offering new avenues for improving cow fertility through marker-assisted selection (MAS).