Effect of suppression of postpartum ovulation on endometrial inflammation in dairy cows.

The objective of this study was to investigate the effect of time of first postpartum ovulation on endometrial inflammation in dairy cows with and without uterine disease during the early puerperal period. Transvaginal follicular puncture (FP) was carried out to suppress postpartum ovulation and formation of a CL until Day 42. Fifty-three lactating Holstein Friesian cows were divided into four groups on the basis of presence (UD+) or absence (UD-) of uterine disease, which was defined as retained fetal membranes and/or metritis, and whether FP had (FP+) or had not been (FP-) carried out. This resulted in the following groups: UD-FP- (n = 15), UD-FP+ (n = 13), UD+FP- (n = 13), and UD+FP+ (n = 12). Cloprostenol was given on Days 55 to 60 postpartum, and GnRH was administered 2 days later for synchronization of ovulation. In the FP- groups, endometrial swab and biopsy samples were collected during the second estrus (approximately Day 40) and during the estrus after synchronization. In the FP+ groups, the same samples were collected during the first estrus (approximately Day 49) and during the estrus after synchronization. The prevalence of positive bacteriologic cultures of the endometrium was not affected by FP (P > 0.05). Histologic signs of endometritis were more severe in UD+FP- cows at second sampling than in UD+FP+ cows (P ≤ 0.05). Endometrial expression of IL1α (in UD- after first sampling and in UD+ after second sampling) and IL1β (in UD- and UD+ after first sampling) was higher (P ≤ 0.05) in FP- cows than in FP+ cows. Regardless of group, cows with histopathologic evidence of endometritis had higher expression (P ≤ 0.05) of IL1α, IL1β, IL6, and TNFα than cows without endometritis. In conclusion, suppression of early ovulation by transvaginal FP enhances clearance of uterine inflammation in postpartum cows.