Blood levels of prostaglandin metabolites (PGFM, PGEM) after parturition in cows with and without retained placenta considering spontaneous calving and dystocia.

Blood samples were taken from 71 Holstein Friesian cows at 0, 3, 24 and 48 hours after parturition. Peripheral plasma concentrations of prostaglandin F2 alpha and E2 metabolites (PGFM, PGEM) were determined by radioimmunoassay. The cows were divided into 4 groups, according to type of calving (spontaneous, dystocia) and discharge of placenta. Group 1: spontaneous calving, shedding of placenta within 12 hours (SC, NRP, n = 19); group 2: spontaneous calving, retained placenta (SC, RP, n = 7); group 3: Dystocia, shedding of placenta within 12 hours (Dys, NRP, n = 32); group 4: Dystocia, retained placenta (Dys, RP, n = 13). The PGFM concentrations decreased within 3 hours after parturition only in NRP cows (groups 1 and 3, p < 0.05). Three hours after calving the animals of group 3 had considerably higher PGFM levels than those in group 4 (0.46 +/- 0.26 vs 0.26 +/- 0.11 ng/ml). Significant decreases (p < 0.05) in PGEM concentrations occurred in cows that shed the placenta within 24 hours after parturition. Cows that retained the placenta showed a significant slower decrease of the PGEM levels. It is concluded that postpartum prostaglandin levels are influenced by stress during parturition (dystocia, transportation) as well as by retained placenta.