Uterine disease in dairy cows is associated with contemporaneous perturbations to ovarian function

Postpartum uterine disease in dairy cows affects ovarian function, but it is unclear how the type and timing of disease relates to ovarian function. To explore associations between uterine disease and contemporaneous ovarian function, postpartum uterine health was evaluated in 17 lactating primiparous Holstein cows that ovulated. Ovarian function was assessed by measuring daily hormone concentrations and the diameter of the largest follicle and subsequent corpus luteum. Metritis (≤14 d postpartum) was associated with reduced follicle diameter (P = 0.002) and tended to reduce plasma estradiol concentrations (P = 0.062) from d 7 to 16 postpartum compared to cows without metritis. Metritis was associated with reduced plasma progesterone (P = 0.026) but not corpus luteum diameter from d 17 to 26 postpartum. Endometritis (≥15 d postpartum) was associated with reduced corpus luteum diameter (P = 0.005) but did not alter plasma progesterone from d 17 to 26 postpartum compared to cows without endometritis. To explore longer term effects of uterine infection on luteal function, non-lactating primiparous Holstein cows received an intrauterine infusion of vehicle control (n = 11) or pathogenic Escherichia coli and Trueperella pyogenes to induce endometritis (n = 12) and corpora lutea were recovered on d 16 of the estrous cycle, 146 d after intrauterine infusion. Intrauterine infusion of bacteria had no effect on plasma progesterone or luteal diameter compared to control, and only altered the expression of 2 of 94 candidate genes (NCF1 and TLR9). Taken together, these studies imply that uterine diseases are principally associated with changes to ovarian function at a time contemporaneous with disease.