The effect of delayed feeding on the post-feeding behaviour of sows

Previous research into oral persistence in pigs has shown that the relationship between motivation and performance of stereotypy is not a simple one, and that non-specific motivational factors such as arousal may be important. For chronically food-restricted sows the time before food arrives is characterised by increasing excitement and arousal which may be carried over into the post-feeding period facilitating the performance of persistent oral behaviour. To investigate this possibility, arousal was manipulated by delaying feeding. Five and 15 min delays were used and sows experienced delayed feeding 1 day in every 4. Principal components analysis (PCA) was used to group the behaviour data into two factors, ACTIVITY/CHEW and NOSE/ROOT/PEN and these scores were then analysed using ANOVA as well as the appropriate individual behaviours. The delay of feeding increased the rate of eating, presumably reflecting increased arousal (P<0.05). ACTIVITY/CHEW scores were highest in 5 min delay sets, and an interaction between day of set and delay length indicated that ACTIVITY/CHEW scores peaked on different days within a set (P<0.05). Time spent chewing was highest on the day of delay (P<0.05), while standing was highest in days 1 and 2 post-delay (P<0.05). The NOSE/ROOT/PEN scores were lower on the day of delay than on other days (P<0.05), and were lowest in the first delay set than in sets later in the trial (P<0.01). It appeared that increasing arousal in the pre-feeding period does affect activity and oral behaviours in the post-feeding period. However, some of the effects appeared in a more extended and diffuse manner, perhaps due to the general disturbance created by the experimental regime and the sows' experience of long-term food restriction.