The post-feeding responses of sows to the daily presentation of food rewards in a test arena

Abstract

It has been suggested that feeding motivation and feeding behaviour are causally related to the performance of persistent oral behaviour in pigs. However, in a previous experiment we showed that the presentation of small food rewards to chronically food-restricted sows in a test arena did not elicit the performance of persistent feeding-like behaviours. In this paper we tested the hypothesis that the arousal generated by the expectation of a daily presentation of a food reward would be ‘channelled’ by a restrictive environment into the expression of persistent feeding-like behaviour. A 2 × 2 factorial design was used, in which sows were presented with either a 1 kg or an 18 g food reward (expected 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 than the sows receiving the small food reward (0.86 vs. 0.66 for the 1 kg 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 was independent of the arousal elicited by the large food reward and not affected by pen size. It appears that feeding motivation is not as closely related to the performance of persistent oral behaviours as had previously been thought. The ‘emotional state’ of the animal around feeding may be an important factor, and chronic food restriction may contribute to this state.