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.