Effects of ergocryptine on plasma prolactin, luteinizing hormone, and progesterone in the periparturient sow.

Effects of ergocryptine (ERG) on the periparturient sow were assessed by measuring changes in prolactin, luteinizing hormone, and progesterone in plasma. Hormones in plasma were determined on samples collected daily from 21 days before parturition until postpartum day (PPD) 21. Administration of ERG completely blocked the initiation of lactation and prevented the surge in prolactin that occurred just before parturition, as compared with effects in control sows. The gestation period was shorter (P less than 0.01) in ERG-treated sows compared with the gestation period in controls. Although the number of pigs farrowed was not different between treated and control sows, the ERG-treated sows did not raise any pigs to PPD 21. Luteinizing hormone concentrations were higher (P less than 0.01) from 10 days before parturition until PPD 21, but plasma progesterone concentrations were not different in treated sows when compared with concentrations in control sows.