Effect of Extended Photoperiod on Performance, Health, and Behavioural Parameters in Nursery Pigs.

Lighting influences the circadian rhythm and physiology of animals. Yet, the influence of light on nursery pigs is not fully understood and results remain controversial. The present study investigated the effects of a prolonged photoperiod on the performance, health, and behaviour of nursery pigs. This study was conducted in one farm and included 288 hybrid nursery pigs. Long (LONG) and short (SHORT) photoperiod animals were exposed to either 16 or 8 h of light per day, respectively. Performance, health, welfare, and behavioural parameters were monitored during a nursery period of five weeks. Short photoperiod piglets tended to have higher weights at the end of the nursery (LONG: 21.59 vs. SHORT: 22.19 kg; p = 0.064) and higher average daily gain (LONG: 385 vs. SHORT: 403 g/day; p = 0.063) compared to the long photoperiod piglets. The LONG piglets had significantly higher fecal consistency scores (0-100) than the SHORT piglets on days 7 (LONG: 21 vs. SHORT: 10; p = 0.039), 11 (LONG: 40 vs. SHORT: 14; p = 0.002), 21 (LONG: 21 vs. SHORT: 8; p = 0.008), and 25 (LONG: 26 vs. SHORT: 11; p = 0.015). The LONG piglets tended to have a slightly higher incidence of aggressive behaviour (LONG: 2.49% vs. SHORT: 2.36%; p = 0.071). No significant differences were found for the remaining parameters (p > 0.1). Under the present conditions, lengthening the photoperiod during the nursery period did not significantly improve the performance, health, and welfare of the pigs.