Effects of eating time on behavioral rhythm and performance of pigs under an intelligent electronic feeding system

An intelligent electronic feeding system has been an ever-increasing pattern in the breeding industry. However, the rotation eating may disrupt the diurnal eating rhythm of some pigs, leading to the health and growth disorder of pigs. This study aims to explore the effects of eating time on the behavior distribution of pig production under the intelligent electronic feeding system. A systematic analysis was also conducted to determine the diurnal proportion of effective and ineffective eating frequency, feed intake, and eating time during the electronic sow feeding (ESF) and pig performance testing station (PPTS). The results revealed that there was the general night eating syndrome of pigs under the rotation eating in the intelligent electronic feeding system, about one-fourth of which ate only at night in the ESF system. The relatively fixed eating order indicated that the herd hierarchy was also an important reason for pig eating time disorder. The ineffective eating behavior of pigs occurred mainly in the daytime, which indirectly increased the likelihood of pigs eating at night in PPTS and ESF. Furthermore, it was probable to reduce the actual number of pigs per station for the less running time of the electronic feeding system and the occurrence of eating at night, according to the operation data from the different areas. More importantly, a further investigation was also made to clarify whether the nighttime feeding of some pigs under the ESF and PPTS feeding patterns caused the disturbance of sleep schedules and retardation of pig growth. Twenty-six miniature pigs were selected to compare the effects of different feeding time on behavioral rhythm and performance of growing pigs. Two groups were divided into daytime feeding and nighttime feeding. The former was designed to mimic the natural eating habits of the pigs, while the latter was for the inconsistent feeding time. It was found that the daytime feeding increased by 135.68 g/d (P<0.1) in the daily feed intake of growing pigs, but there was no significant difference in the daily gain between the two groups. The eating behavior of the growing pigs in the daytime feeding group was mostly eating, drinking, and scratching during the daytime, as well as lying at nighttime. By contrast, the eating behavior of growing pigs in the nighttime feeding group was mainly concentrated at the feeding time of 19:00 and the alternating time of daytime and nighttime at 7:00. The daytime feeding increased by 44.28, 14.22, and 61.95 min/d (P<0.05) in the duration of feeding, drinking, and lying, respectively, whereas, decreased by 48.75, 57.40, and 20.30 min/d (P<0.05) in the duration of standing, walking, and scratching, respectively. Therefore, the nighttime feeding disrupted the normal circadian eating, drinking, and lying behavior rhythm of some growing pigs, particularly for the occurrence of bad mood signals, such as standing and scratching. Consequently, the intelligent electronic feeding system destroyed part of the eating rhythm, leading to the growth difference in individual pigs. Some recommendations were also given to arrange the number of pigs in each feeding station for the optimal running time of the intelligent electronic feeding system during pig breeding.