The purpose of this study was to investigate the effects of light exposure on farrowing performance in sows. Thirty sows were moved to the farrowing unit at d 110 of gestation and assigned a treatment: 12 h light/12 h dark cycle (Dark) or 24 h light (Light). Treatments began upon entry into the farrowing unit. Video was recorded continuously from initiation of the treatments until completion of farrowing. Data collected included duration of farrowing, birthing interval, and behavior during farrowing. Additionally, the number of total born, liveborn, and stillborn piglets was recorded. Gestation length was different between treatments, with a shorter gestation in Dark treatment sows than Light treatment sows (116.4 vs. 117.1 ± 0.2 d, respectively; p = 0.027). The total duration of parturition and number of liveborn did not differ (p = 0.393). Number of stillborn piglets between treatments did differ (p = 0.018). Dark had more stillborns compared to Light treatment sows (1.5 vs. 0.7 ± 0.2 piglets, respectively). Neither the interval between piglets nor farrowing behavior differed between treatments (p > 0.100). The results from this experiment indicate that a sudden change in photoperiod has the potential to impact the gestation length of sows and number of stillborn pigs.

The purpose of this study was to investigate the effects of light on farrowing performance in sows. Thirty sows were moved to the farrowing unit at d 110 of gestation and were assigned one of two treatments: 12 h light/dark cycle (Dark) or 24 h light (Light). Treatments were initiated upon entry into the farrowing unit until completion of farrowing was confirmed. For Dark sows, the farrowing crates were structured with light blocking tarps that were lowered at 1900 hr and raised at 0700 hr daily. Video recording devices were installed above all sows and continuous video was recorded from initiation of the treatments until farrowing was complete. Data collected included duration of farrowing, birthing interval, number of stillborn piglets as an indirect measure of dystocia, total born, and liveborn piglets. All statistical analyses were performed using the mixed procedure of SAS, where the experimental unit was individual sow. Funding for this project was provided by the National Pork Checkoff and the U.S. Pork Center of Excellence. Dark sows were more likely to give birth closer to their due date compared to Light sows (1.34 vs. 2.16 ± 0.24 days relative to a 115-day due date, respectively; P = 0.02). Total duration of parturition did not differ between treatments (P = 0.56). Number of liveborn piglets between treatments did not differ (P = 0.68), however the number of stillborn piglets between treatments was different (P = 0.02), where Dark sows had a higher incidence of stillborn piglets compared to Light sows (1.52 vs. 0.65 ± 0.25 stillborn piglets/litter, respectively). The interval between piglets did not differ between treatments (P = 0.93). It is hypothesized that the effects on due date and increased incidence of stillborn piglets was caused by increased stress due to visual isolation in the Dark sows.