Development of a behavioural test of sensory responsiveness in the growingpig

The responses of individual growing pigs to 60 stimuli from five sensory ca tegories were evaluated as an initial step in developing a behavioural meas ure of welfare. Rigs were exposed to the stimuli in a test pen after being trained to eat from a food box adjacent to a stimulus presentation box. The pen design allowed easy expression of approach/avoidance behaviour by the pig. Five variables were measured - change in mean approach/avoidance dista nce from the food box, change in frequency of elimination, change in freque ncy of turning away from the stimulus box, latency to return to the food bo x after stimulus presentation, and latency to enter the stimulus box. The m ost robust measure of responsiveness was change in approach/avoidance dista nce, The strongest and most consistent aversive responses were obtained to auditory stimuli. There was little or no response to olfactory stimuli. Onl y two visual stimuli, which incorporated a black cross on a yellow backgrou nd, elicited strong aversive responses. Other novel visual stimuli elicited positive responses. Responses to tactile stimuli were generally positive, mainly because they were administered by the experimenter and the pigs were familiar with handling by humans. Because there was significant variation between individual pigs, we propose that stimuli, which elicit high respons iveness but with little variation should be used in future tests of differe nces in responsiveness between treatments that may be indicative of stresse d and unstressed pigs. (C) 2000 Elsevier Science B.V. All rights reserved.