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farrowing, light cycle, photoperiod, sow


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, number of total born, liveborn, and stillborn piglets were 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). 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). The interval between piglets nor behavior differed between treatments (P > 0.100). The results from this experiment indicate that a sudden change in photoperiod has the potential to impact gestation length of sows and number of stillborn pigs.