Association of calving factors and labor duration with postpartum uterine health in Holstein cattle.

Abstract

The objective of this observational study was to investigate the association between the duration of labor, calving assistance, and uterine diseases, as well as estimate a reference time to be used as a guideline for providing calving assistance based on the health outcome of metritis. Holstein cows (n = 496) were enrolled approximately 3 wk before their expected calving date. Cameras were used to record calving behavior of a subset of cows (n = 286), where the occurrence of calving assistance (forced extraction lasting a minimum of 5 s), calving location, and pen movement during labor were recorded. Calf weight was recorded at birth, retained fetal membranes (RFM) was diagnosed 24 h after calving and metritis was diagnosed based on vaginal discharge measured at 6 and 12 DIM. Subclinical and clinical endometritis (ENDO) was based on cytological examination and vaginal discharge at 40 ± 5 DIM. Duration of stage II labor was estimated as the time from the appearance of the amniotic sac until the calf was expelled. Calving was assisted for 14% of cows. Duration of labor ranged from 11 to 173 min (mean ± SD = 57.2 ± 32.0) in unassisted cows and 49 to 232 min (122.7 ± 51.2) in assisted cows. As calf weight increased, the duration of labor increased (slope, m = 1.16 ± 0.34). For every 5-kg increase in calf weight, there was 1.47 greater odds of RFM (95% CI = 1.38-2.08). Cows assisted during labor were at 3.67 higher odds of metritis when compared with unassisted cows (95% CI = 1.92-7.05). A quadratic relationship existed between metritis and duration of labor for assisted cows, where the predicted probability of metritis was greatest at the shortest (49 min; 69.2%) and longest (232 min; 100%) durations of labor, but the lowest predicted probability of metritis (22.1%) was at approximately 130 min. Predicted probability of metritis in unassisted cows was not affected by duration of labor. Neither duration of labor nor the occurrence of calving assistance was associated with the development of RFM or ENDO. Providing assistance either too early or too late during stage II labor may result in an increased risk of metritis; the results of this study suggest that intervention 130 min after the appearance of the amniotic sac may be associated with a reduced incidence of metritis. Further research is required to determine how progression of labor and timing of intervention affects the development of uterine diseases.