A note on the effect of handling quality prior to mixing on behaviour at mixing in pigs

Previous research has raised the possibility that levels of aggression betw een pig may be influenced by their state of arousal and excitement at the t ime of mixing. This may, in turn, be affected by factors such as the way in which pigs are handled prior to mixing. We attempted the first systematic test of this idea. Sixty four growing pigs were housed in groups of four fo r 4 weeks to allow them to become familiar with their group mates. Each pig was then tested in a 10 min encounter with another pig in an unfamiliar te st pen. Pigs were either handled gently (G) or firmly (F) on their way to t he encounter. In addition, pigs either met a familiar (F) or an unfamiliar (U) pig in the test pen. Thus, there were four types of encounter (FF FG, U F, UG) with N = 8 tests of each. Two-way analysis of variance showed no eff ects of handling quality and no interactions between handling quality and f amiliarity on behaviour during encounters. Unfamiliar pigs showed higher le vels of aggressive behaviour. Any fights were stopped immediately. On a sec ond test day, pigs were handled as previously, but all now encountered a fa miliar individual. Again, there were no effects of handling quality or inte ractions between handling quality and familiarity. The results, thus, faile d to support the idea that the quality of handling prior to mixing influenc es the levels of aggression subsequently observed. (C) 2001 Elsevier Scienc e B.V. All rights reserved.