Effect of on farm mixing and slaughter strategy on behaviour, welfare and productivity in Duroc finished entire male pigs

摘要

Animal welfare may be hampered due to a higher incidence of aggressive and sexual behaviours in entire males compared to castrated pigs. The aim of this study was to investigate the effect of mixing strategies on behaviour and physiological indicators of welfare and performance. Ninety-six entire male pigs were reared following either a wean to finish strategy in which no mixing was allowed after 14 days of age (WF, 48 pigs) or following a conventional strategy in which piglets were randomly mixed when entered to the transition and fattening pens at 72 days of age (MP, 48 pigs). Pigs were allocated in groups of 12 in 8 pens (4 WF pens and 4 MP pens). Two pens per housing system were slaughtered by split marketing (SM) in three days and the other two pens were slaughtered penwise (PW) when individual or pen mean body weight was around 120 kg, respectively. Saliva samples of all males were collected at 75,105 and 150 days of age and skin lesions evaluated at 75, 90, 105, 125 and 150 days of age. Three more saliva samples and 2 skin evaluations were performed from the pigs of the SM treatment that remained in the pen after each slaughter batch. Behaviour was recorded by direct and video recording six times (between 85 and 155 days of age). Time budget was assessed by scan sampling every 10 min, whereas focal sampling of all pigs in a pen was also performed to record all aggressive events and mounts or attempts to mount the 8 min in between the 2 scans. Pigs were individually weighed and loin and backfat measured every three weeks, and individual feed intake automatically recorded during the entire fattening period (73-155 days of age). Carcass skin lesions were assessed. No significant differences between MP and WF pigs in time budget nor on sexual or agonistic behaviour nor performance data were observed. Cortisol levels did not significantly differ between WF and MP pigs, but a significant increase over time (P<0.05) was observed for SM slaughtered pigs (for both MP and WF pigs). After both SM batches, more skin lesions on the remaining pigs were recorded in the MP compared to WF pigs (P<0.01 and P<0.1, respectively). In accordance, a significantly higher incidence of carcass skin lesions was found for MP and SM pigs compared to WF and PW (P<0.01 and P<0.05, respectively). The present results suggest that the welfare benefits (i.e. lower skin lesions) of a WF system were mainly associated with an easier hierarchy reestablishment after SM, but no other long term effects during the rest of the fattening period were observed. (C) 2012 Elsevier B.V. All rights reserved.