Summary
European researchers compared the effects of two different pen designs on tail-biting in pigs. PEN1 was a traditional Danish “finisher” pen, while PEN2 was inspired by a Swedish “finisher” pen design, requiring different slurry channels, floors, housing equipment, ventilation, and reduced group size. The pigs were liquid fed three times a day using a commercial diet and were given straw as enrichment material. Tail damage observations were carried out daily by the stockperson, and bitten pigs were ear tagged. The study found that there were significantly more tail injuries observed in PEN1 compared to PEN2, particularly during the pig growth period between 30 to 60 kg. Aggressive behavior tended to be more common in PEN1 compared to PEN2, but there was no difference in the duration of aggressive behavior between the two pen designs. Pigs in PEN2 spent more time participating in tail and straw-directed behavior compared to PEN1. Using the Welfare Quality Protocol, PEN1 received an “enhanced” score while PEN2 received an “excellent” score. A strength of the study is the large sample sizes of pigs placed in PEN1 and PEN2, which increases the reliability of the results. A limitation is that the study relied on one trained research technician to score tail damage, and therefore interrater reliability of the scoring system was unavailable. Additionally, it was also unclear if the research technician was kept blind to which pen each pig was housed in, to help reduce the potential of bias. The study implies that an increase of space allowance, more area of solid flooring, and smaller pig group sizes results in fewer pigs with damaged tails.
Tail biting is a welfare and economical concern in modern pig production. One common preventive measure used throughout the world is tail docking, which is generally considered one of the most effective methods for limiting tail biting. However, tail docking is a painful mutilation and systematic tail docking is not allowed in the EU. Therefore, the aim was to compare pig behaviour and the prevalence of tail biting in finishing pigs with intact tails housed in two different pen designs under Danish commercial conditions. PEN1 was a traditional Danish pen and PEN2 was inspired by Swedish finisher pen design and had a larger proportion of solid floor area (PEN1: 1/3 and PEN2: 2/3), reduced group size (PEN1: 15 and PEN2: 12), increased space allowance per head (PEN1: 0.7 m2 and PEN2: 0.89 m2) and straw allocated on the floor (PEN2) whereas straw was provided in a straw rack in PEN1. Tail damage observations were carried out daily by the stockperson and every 2 weeks one trained research technician assessed tail damages according to a tail scoring system. Tail lesions were observed in 51% of PEN1 and in 11% of PEN2 (P < 0.001). PEN1 had higher prevalence of tail damages than PEN2 (23% v. 5%, P < 0.001). Behavioural observations were carried out by the use of video recordings. Pigs in PEN2 tended to spend more time on tail-directed behaviour than pigs in PEN1 (P = 0.07), whereas pigs in PEN1 tended to spend more time on ear-directed behaviour (P = 0.08). Pigs in PEN2 spent more time on straw-directed behaviour compared to pigs in PEN1 (P < 0.001). Pen design did not affect time spent on other penmate-directed behaviour. In addition, the level of welfare between the two pen designs was compared using the Welfare Quality® protocol. PEN2 received an overall score of ‘excellent’ while PEN1 scored ‘enhanced’. PEN2 scored higher on all principles besides ‘good health’, where PEN1 scored better on lameness and wounds. The main measurements accounting for the differences were water supply, huddling, tail biting, social behaviour and fear of humans. In conclusion, the combination of increased space allowance, increased area of solid flooring, straw allocated onto the floor and reduced group size (PEN2) resulted in fewer tail damaged pigs and a better overall welfare assessment, despite a tendency for more tail-directed behaviour.