Reduced growth rate and changed behaviour after surgery
Behavioural observations suggest that piglets experience pain for up to 5 days after castration (increased abnormal behaviours, reduced play behaviour and overall activity) (Wemelsfelder and van Putten, 1985).
Other studies have confirmed that some behaviour changes persist beyond 24 hours (Hay et al., 2003). For instance, tail wagging is more frequently observed in castrated pigs during the 4 days after castration, even though the difference is not always significant. Scratching the rump reaches a peak 24 hours after castration but still continues on the fourth night following castration.
Finally, it should be emphasized that castration has long term effects on growth performance and feed conversion (EFSA, 2004). Indirectly low growth performance and feed conversion has negative effects on the environment.