EFFECTS OF SIMULATED LAIRAGE CONDITIONS ON THE PHYSIOLOGY AND BEHAVIOR OF PIGS

The responses of pigs to being driven and mixed together in lairage we re investigated. Five groups of six and five groups of seven 70 kg pig s were transported for 40 minutes on a lorry and then subjected to one of the following treatments: two groups were driven down a passage; f our groups (A to D) were mixed together for one hour (A and B together , and C and D together); and, four groups were driven down the passage and then mixed ('combined treatment'), The pigs' behaviour was record ed, skin damage was scored and saliva samples were taken for analysis of cortisol. The initial journey increased the pigs' salivary concentr ation of cortisol, Their behaviour while being driven was not correlat ed with the concentrations of cortisol after they were driven and cort isol concentrations did not increase relative to post-transport levels . The frequency and duration of fighting when they were mixed were pos itively correlated with their level of aggression in the home pen and with the increase in concentrations of cortisol when they were mixed. One hour after they had been mixed, the concentrations of cortisol had decreased relative to post-transport levels. After the combined treat ment, the correlations observed for the mixing treatment were absent, and the concentrations of cortisol increased relative to post-transpor t levels. Skin damage was greatest after the groups of pigs were mixed , The responses observed indicate that the combined effects of driving and mixing, which are very common in lairage, were greater than the e ffects of driving or mixing alone.