A dairy herd-level study of postpartum diseases and their association with reproductive performance and culling.

The objectives of this study were to quantify the herd-level prevalence of postpartum diseases in a large number of dairy farms, and to identify prevalence alarm levels of these diseases based on association with a low prevalence of success at first service, with a high prevalence of pregnancy loss following pregnancy diagnosis at first service, and with a high prevalence of postpartum culling. A total of 126 commercial dairy herds were enrolled in this cohort study, and the herd was the unit of interest. Twenty cows from every herd were enrolled during the study period (a total of 2,520 lactating cows in the study). Cows were diagnosed with hyperketonemia, retained placenta, displaced abomasum, purulent vaginal discharge, cytological endometritis, leukocyte esterase endometritis, and prolonged anovulation. The prevalence of each of these diseases was computed for every herd. The study outcomes were the prevalence of success at first service, the prevalence of pregnancy loss following pregnancy diagnosis at first service, and the prevalence of postpartum culling (≤60 d in milk). Descriptive statistics of disease and outcome prevalence were computed. Logistic regression models were used to identify prevalence alarm levels associated with poor outcome prevalence. Median herd prevalence for hyperketonemia, retained placenta, displaced abomasum, purulent vaginal discharge, cytological endometritis, leukocyte esterase endometritis, and prolonged anovulation were 18.8, 4.9, 4.0, 5.0, 29.4, 43.8, and 35.2%, respectively. Herds were defined as having low prevalence of success at first service if <40.0%, as having a high prevalence of pregnancy loss if ≥6.3%, and as having a high prevalence of postpartum culling if ≥13.3%. Risk factors for herds having a low prevalence of success at first service were ≥11.8% hyperketonemia, ≥5.0% purulent vaginal discharge, ≥18.8% cytological endometritis, ≥35.3% leukocyte esterase endometritis, ≥21.0% prolonged anovulation, and ≥4.0% of displaced abomasum. Risk factors for herds having a high prevalence of pregnancy loss were ≥5.0% purulent vaginal discharge and ≥4.9% retained placenta. Risk factors for herds having a high prevalence of postpartum culling were ≥23.1% hyperketonemia, ≥4.9% retained placenta, and ≥4.0% displaced abomasum. Overall, postpartum diseases were prevalent in these dairy herds and alarm levels were identified as risk factors for poor reproductive performance and increased culling.