THE POST-FEEDING RESPONSES OF SOWS TO THE DAILY PRESENTATION OF FOOD REWARDS IN A TEST ARENA

It has been suggested that feeding motivation and feeding behaviour ar e causally related to the performance of persistent oral behaviour in pigs. However, in a previous experiment we showed that the presentatio n of small food rewards to chronically food-restricted sows in a test arena did not elicit the performance of persistent feeding-like behavi ours. In this paper we tested the hypothesis that the arousal generate d by the expectation of a daily presentation of a food reward would be 'channelled' by a restrictive environment into the expression of pers istent feeding-like behaviour. A 2 x 2 factorial design was used, in w hich sows were presented with either a 1 kg or an 18 g food reward (ex pected to engender different levels of arousal) in a 16 m(2) or 4 m(2) sand-bedded test pen during a 40 min observation period, each day for 26 days. It was shown that sows receiving the large food reward stood for a greater proportion of the time after food reward consumption th an the sows receiving the small food reward (0.86 vs. 0.66 for the 1 k g and 18 g food reward, respectively; P < 0.05). Neither pen nor food reward size affected chewing behaviour or sand-directed behaviour (P > 0.05). The proportion of time spent chewing increased with test day ( 0.15 vs. 0.36 for test day 1 and day 26, respectively; P < 0.01) but w as independent of the arousal elicited by the large food reward and no t affected by pen size. It appears that feeding motivation is not as c losely related to the performance of persistent oral behaviours as had previously been thought, The 'emotional state' of the animal around f eeding may be an important factor, and chronic food restriction may co ntribute to this state.