More tail lesions among undocked than tail docked pigs in a conventional herd

The vast majority of piglets reared in the EU and worldwide is tail docked to reduce tail biting, even though the EU animal welfare legislation bans routine tail docking. Some well-managed farms experience very low levels of tail biting among tail docked pigs. At this point, there is little scientific evidence regarding the effect of tail docking on tail biting prevalences in these kinds of conventional farms. The aim of this study was therefore to compare the prevalence of tail injuries between docked and undocked pigs in such a well-managed conventional piggery in Denmark where pigs in usual practice were tail docked. This study included 1922 DanAvl Duroc × (Landrace × Large White) pigs (962 docked and 960 undocked). Docked and undocked pigs were housed under the same conditions, but in separate pens within the same stable. Pigs had ad libitum access to commercial diets in a feed dispenser. Straw was provided daily on the solid floor (10 g per pig per day), and each pen had two vertically placed soft wood sticks. Pigs were individually earmarked and gender was determined just before weaning. The stockpersons recorded antibiotic treatments, pigs moved to hospital pens and euthanized pigs. From weaning to slaughter, a trained technician recorded tail damages (injury severity and freshness) every second week. No tail damages were observed within the tail docked group, whereas 23.0% of the undocked pigs got tail bitten. On average, 4.0% of the pigs had a tail lesion on tail inspection days. The results showed more pens with pigs weighed 30-60 kg with tail lesions (34.3%; P < 0.05) than in pens with pigs weighing 7-30 kg (13.0%) and 60-90 kg (12.8%). Furthermore, more undocked pigs had to be moved to a hospital pen (P<0.05). Finally, abattoir meat inspection data revealed more tail biting remarks in the undocked group (P<0.001). In conclusion, this study suggests that housing pigs with intact tails even in well- managed conventional herds will increase the prevalence of tail bitten pigs considerably, and pig producers will need more hospital pens. Furthermore, the abattoir data indicate that meat inspection data severely underestimate the number of pigs experiencing to be tail bitten during the rearing period.