Induction of parturition in swine with prostaglandin F 2α, estradiol benzoate and oxytocin

Abstract

Pregnant sows and gilts were administered either 0, 2.5, 5, 10 or 20 mg prostaglandin F 2α (PGF 2α) intramuscularly on Day 112 or 113 of gestation at 0800 h in an effort to induce parturition. The average interval from PGF 2α injection to farrowing was 55.1 ± 5.7, 29.4 ± 3.1, 32.1 ± 4.6, 27.8 ± 1.8 and 26.9 ± 1.1 h for 0, 2.5, 5, 10 and 20 mg, respectively. All PGF 2α treatments increased (P < 0.01) over controls the number of sows farrowing 23 to 33 h after injection. The average gestation length was significantly shorter in treated gilts; however, no detrimental effect on pig performance or pig survivability was observed. A second trial evaluated the effect of a 10-mg dose of PGF 2α on the induction of parturition in sows in order to obtain a majority of sows farrowing within normal working hours (0700 to 1700 h). The interval from injection to farrowing was decreased (P < 0.05) by PGF 2α treatment (66.2 ± 5.3 vs 28.1 ± 2.2 h). Fifty-seven percent (P < 0.05) of PGF 2α-treated sows farrowed between 0700 and 1700 h as compared to 13.6% for control sows. A third trial was conducted to examine a sequential treatment of PGF 2α and oxytocin to control the time of parturition more precisely. Sows receiving only 10 mg of PGF 2α farrowed on an average 31.1 ± 1.4 h after injection. The injection of 40 IU oxytocin 24 to 28 h after PGF 2α decreased (P < 0.05) the interval from PGF 2α to farrowing (28.1 ± 0.9 h). The addition of oxytocin increased (P < 0.05) the number of sows farrowing within 3 h of injection (33 vs 86% for PGF 2α and PGF 2α + oxytocin treatments, respectively). A fourth trial was designed to determine if the addition of exogenous estradiol benzoate (EB) to a sequential treatment of PGF 2α and oxytocin would improve the predictability and synchronization of the induced parturition. Sows were assigned to receive either saline, 10 mg PGF 2α + 40 IU oxytocin or 10 mg PGF 2α + 5 mg EB + 40 IU oxytocin. The addition of EB reduced (P < 0.01) the variance in the interval from oxytocin to farrowing and added precision to the predicted time of induced parturition.