2007 年 53 巻 2 号 p. 279-288
The aim of this study was to evaluate the changes in plasma concentrations of estrone sulfate (E1S) and estradiol-17β (E2β) during the peripartum period (from day 10 prepartum to day 1 postpartum) associated with and without retention of fetal membranes (RFM) in Holstein-Friesian cattle (n=42). Plasma samples were analyzed for E1S and E2β by ELISA. All parturitions were spontaneous and normal. Of 38 cattle delivering singletons, 29 had no RFM (singleton-normal group) and nine had RFM for more than 12 h (singleton-RFM group). Four cows gave birth to twins, and each twin had its own fetal membrane (FM). Two twinning cows expelled both FMs normally within 12 h (twin-normal group). In the remaining 2 twinning cows (twin-RFM group), the FM was expelled normally for one twin (first), while the FM of the other (second) was retained. There were no significant differences in the E1S concentrations or their increments from the concentrations on the preceding day between the normal and RFM groups of singleton cows on any peripartum day. The mean plasma E2β concentrations on each day from day 10 to day 3 prepartum were significantly lower (P<0.05) in the singleton-RFM group compared with the singleton-normal group; however, on days 2 and 1 prepartum, the increments in the E2β concentrations from the concentrations on the preceding days were significantly higher (P<0.05) in the singleton-RFM group than in the singleton-normal group. Thus, the plasma E1S concentrations just before parturition may not be associated with RFM. In the cows with RFM, the lower plasma E2β concentrations that were found prior to day 2 prepartum may have been associated with immature placentomes, and the rapid rise in plasma E2 β within 1 to 2 days prior to calving may have produced asynchrony of placental and/or fetal maturation in relation to calving, thus resulting in RFM.
