Peripartal endocrine changes associated with retained placenta in dairy cows.

Peripheral serum concentrations of prostaglandin F(2)alpha metabolite (PGFM), cortisol, and progesterone (P(4)) were determined in cows that retained placentae (RP; n = 18) and cows that did not retain placentae after parturition (NRP; n = 28). Blood samples collected from Day 15 before until Day 15 after parturition were assayed. Significant increases (P < 0.05) in PGFM concentrations occurred in RP cows between Days 7 and 6 before parturition compared with NRP cows. There were no differences in the interval required to attain peak concentrations of PGFM and the interval required to reach basal concentrations after parturition in both groups. However, the amount of PGFM secreted during the peripartum period was significantly higher in RP cows (P < 0.01). Starting from Day 6 before parturition, serum cortisol concentrations in RP cows increased significantly to peak levels 3 d before parturition (P < 0.05). Cortisol levels decreased to basal concentrations in RP cows on Day 1 postpartum. The peripartal serum P(4) concentrations in RP and NRP cows did not differ. The results indicate that prepartal PGFM and cortisol increases may constitute reliable indicators of retained placenta in dairy cows.