Effect of an automatic feeding system on growth performance and feeding behaviour of pigs reared outdoors

Nine Mora Romagnola and 10 Large White x Mora Romagnola growing pigs were reared outdoors. In both groups ad libitum feed was provided. Conventional pigs received it twice a day, distributed in two long troughs. Inside the corral of the second group, an automatic station was set up for: feed distribution, pigs weighing, and control by an analog camera. Thus the self-feeders received feed ad libitum individually by the automatic system, divided into small quantities at meal times. During the experiment the analog camera was used over 24 hours each day, to collect pictures of pigs in order to investigate their behaviours. For each picture the day and hour, the number of visible pigs and their behaviours were recorded and a statistical analysis of data, which was expressed as hourly frequencies of behavioural elements, was performed. Moreover to highlight "active" and "passive" behaviours between the groups, two categories "Move" and "Rest" were created grouping some behavioural elements. With regard to performance, conventional pigs reached a higher total weight gain (56.1 +/- 2.42 kg vs 46.7 +/- 2.42 kg; P=0.0117). But the feed conversion index (FCI) of both groups was similar. The self-feeders had consumed less feed than conventional animals. The feeding system seems to influence behaviours. The percentage of time spent in Eating activity differs (P<0.0001) between the self-fed (median 24.6%) and conventional pigs (median 10.9%). The resulting more regular eating trend of self-feeders influenced the daily activities distribution. The behavioural category Rest (median: self-feeders 55.0% vs 71.4% conventional pigs) was dominant, with conventional pigs becoming more restless, particularly at meal times. This type of feeding competition and aggressive behaviour did not happen in the self-feeders due to the feed distribution system. The self-feeder results showed that pigs eat at the automatic station both day and night. The animals perform on average 3 visits per hour at night and 10 during the day, with an average duration of some minutes (from 3 to 5 approximately).