Effects of induction on the farrowing process and piglet blood parameters at the time of farrowing

Abstract

Historically, sows have been induced to farrow using prostaglandin followed by an injection of oxytocin 24 h later. Benefits of induction can include decreased rate of stillbirths, dystocia, and postnatal mortality along with increasing the likelihood of farrowings being attended. Several studies have indicated that oxytocin administration may negatively impact fetal oxygen supply during parturition, potentially from umbilical cords breaking prior to birth, resulting in increased preweaning mortality. Therefore, the objective of this study was to determine if various induction protocols impact umbilical cord breakage and fetal blood parameters at birth. Fifty-eight primiparous and multiparous sows were assigned to one of three treatments: no induction (NO; n = 24) or 2 cc prostaglandin administered on day 114 of gestation followed by either 1 cc of oxytocin 24 h later (OXY24; n = 13) or 0.5 cc of oxytocin at 6 and 12 h after prostaglandin (OXY6; n = 21). Details of the farrowing process were recorded, and umbilical cord blood was collected from piglets at birth and evaluated on an iSTAT machine using an Abbott EC8+ test cartridge. There were no differences in total born, number born alive, stillborns, mummies, or assistance needed during farrowing. Induced sows were more likely to farrow by day 115 compared to naturally farrowing sows (P = 0.02). Sows in the OXY24 treatment tended to have longer farrowings when compared to both NO and OXY6 (4.8 vs. 3.6 vs. 3.9 h; P = 0.09). Colostrum from OXY6 sows tended to have a greater amount of lactose present than NO and OXY24 (P = 0.05). Colostrum from sows with longer gestation lengths had a higher percentage of fat (P = 0.03). Piglets born from NO sows had higher base excess, total carbon dioxide, and glucose, which suggests that these piglets had prolonged moments of asphyxiation (P < 0.01). OXY24 piglets had the lowest blood pH which is indicative of hypoxic birthing conditions (P < 0.01). Preweaning mortality was driven largely by a low birth weight coupled with low colostrum intake (P = 0.03). All piglets, regardless of treatment, displayed signs of stress during farrowing. Induction did not influence preweaning mortality but has the potential to decrease the incidence by increasing attended farrowings.

Keywords: farrowing; induction; piglet.