Evaluation of the relative gene expression of FGF2, HAS2, BCL2, VEGFA, and PGR in repeat-breeder cows undergoing cyclicity or acyclicity.

Repeat breeder syndrome (RBS) is one of the main reproductive failures in mono-ovulatory dairy cattle. The differential relative expression of several important genes in the ovary and uterus were evaluated in repeat-breeder dairy cattle. Cows classified as RBS, defined as those that had failed to conceive after at least three consecutive inseminations, with no clinical abnormalities. The selected cows were divided into two groups: repeat-breeder dairy cows undergoing cyclicity (control group) (n = 8) or acyclicity (n = 6). Granulosa cells (GCs) and endometrium were collected from both groups to evaluate the relative expression levels of target genes (fibroblast growth factor 2 [FGF2], hyaluronan synthase 2 [HAS2], B-cell lymphoma 2 [BCL2], vascular endothelial growth factor A [VEGFA], and progesterone receptor [PGR]). The relative expression levels of FGF2 mRNA in GCs (0.34-fold and -65.84 %) and PGR mRNA in endometrium (0.09-fold and -90.53 %) were lower (P < 0.05) in acyclic cows relative to cyclic cows. The relative expression levels of HAS2 and BCL2 mRNA in GCs tended to be lower by 0.40-fold (-59.85 %, P = 0.084) and 0.54-fold (-45.84 %, P = 0.065) in acyclic cows relative to cyclic cows. However, none of the relative expression levels of VEGFA in the ovary and uterus differed between groups (P > 0.10). These results provide a comparison of differential gene expression in repeat-breeder dairy cows undergoing cyclicity and acyclicity, suggesting a role in ovarian follicular growth and uterine function.