RESPONSES OF SLAUGHTER PIGS TO TRANSPORT AND LAIRAGE SOUNDS

The behavioral and physiological responses of pigs to transport and su bsequent exposure to slaughterhouse sounds were examined. Ferry-one gr oups of four slaughter pigs were separately loaded onto a lorry and tr ansported for 25 min. Another 43 groups were loaded onto the lorry whi ch then remained stationary for 25 min. Following unloading pigs were moved to a race with a length of 15 m and a width of 1.5 m. Either one of the following sounds was played at 85 dB(A) for 10 min: Pigs in fr ont of the restrainer, Machines in lairage, White Noise, or Control (n o sound). Pigs exposed to the Machines and White Noise treatment spent significantly more time close to their group-mates compared with Cont rol pigs, with pigs subjected to the Pig sound being intermediate. Tra nsported pigs spent less time exploring the race and were less active than pigs from the stationary lorry. Heart rate was higher during tran sport than during the stationary period. In contrast, during unloading , the sound exposure period and the post-sound period, heart rate was lower in the transported groups. Heart rate did not significantly diff er between sound treatments. Salivary cortisol concentrations were sig nificantly higher after transport than after the stationary period and remained higher for transported pigs after the sound exposure period. Cortisol levels did not differ significantly between sound treatments . it is tentatively suggested that social support from conspecifics ma y protect pigs from potentially adverse effects of exposure to lairage sounds. (C) 1998 Elsevier Science Inc.