Effectiveness of different farrowing induction protocols in sows using alphaprostol on day 114 of gestation.

Farrowing induction in sows is frequently applied and different protocols were described. Most studies induce farrowing between day 111 and 113 of gestation, but hardly any later during gestation. The aim of this study was to investigate the effects of different induction protocols when applied on d114 of gestation. We randomly assigned 118 sows to four treatment groups: single injection of prostaglandin (1×PG), prostaglandin combined with oxytocin 24 hours later (PG+OT), half the dosage of prostaglandin twice with six hours interval (2×1/2PG), and a control group of which farrowing wasn't induced. All injections were administered intramuscularly in the neck on day 114 of gestation. A significantly higher percentage of sows started farrowing between 22 and 32 hours after induction in the PG+OT-group (68 per cent) and the 2×1/2PG-group (52 per cent) compared to the control group (23 per cent). The 1×PG-group (46 per cent) tended to differ from the control group (P=0.087). More sows from the PG+OT-group were constipated at farrowing (P=0.042). Farrowing duration, birth interval, per cent stillborn piglets, dystocia and other variables were similar between the groups. In the present herd and with continuous farrowing supervision, applying PG+OT or 2×1/2PG on d114 of gestation was efficient to induce onset of farrowing in most of the sows 22-32 hours after induction without considerable negative effects.