THE EFFECTS OF EARLY CONTACT WITH HUMANS ON THE SUBSEQUENT LEVEL OF FEAR OF HUMANS IN PIGS

This study examined the influence of early handling at various ages on the subsequent behavioural responses of pigs to humans. Piglets in handling treatments were handled daily at either 0-3 weeks. 3-6 weeks, 6-9 weeks or 9-12 weeks of age. Handling in these treatments involved individual introduction for 2 min to an experimenter in a small arena. The experimenter squatted during the introduction and attempted to gently pat or stroke the pig whenever it approached closely. Piglets in a fifth treatment received no human contact other than that received during routine husbandry. Piglets in the 0-3 week and 9-12 week handling treatments displayed reduced levels of fear of humans at 18 weeks of age in comparison with those in the non-handling treatment. For example, pigs handled from 0-3 weeks and 9-12 weeks were quicker (P<0.05) to enter within 0.5 m of the experimenter and were quicker (P<0.01) to physically interact with the experimenter in a standard test at 18 weeks than pigs in the non-handled treatment. In the behavioural tests conducted at 20, 22 and 24 weeks of age there were no significant (P>0.05) treatment effects on the behavioural responses of pigs to humans. As previously found, the results indicate that handling early in life may influence the subsequent behavioural responses of pigs to humans. In the present study, the periods 0-3 weeks and 9-12 weeks were the ones in which handling had the most pronounced effects on behaviour at 18 weeks of age. It is possible that the 0-3 week period was effective since it may represent a sensitive period for socialization in which social contact may influence subsequent social relationships, while the 9-12 week period was effective because it involved the most recent intense handling. However, in contrast to earlier results, those of the present study indicate that the effects of early handling may dissipate or be overriden by the effects of handling later in life.