Fresh wood reduces tail and ear biting and increases exploratory behaviour in finishing pigs

• We tested three low-cost point-source objects feasible for commercial pig farming.
• The study was carried out on a commercial farm with undocked pigs.
• Freshly cut young tree trunks reduced mild but not severe tail and ear biting.
• Polythene pipes and freshly cut tree trunks increased explorative behaviour.
• The increase in explorative behaviour persisted even after 2.5 months of exposure.

Chewing and rooting are high behavioural priorities in pigs. Lack of suitable materials can lead to abnormal behaviours such as tail and ear biting. In commercial farming, slatted floors limit the use of straw, and various point-source objects have therefore been developed. The crucial challenge is to design objects that improve welfare at minimal material and labour costs. The aim of this study was to test three low-cost objects: branching metal chains, polythene pipe crosses and fresh wood. The study was carried out on undocked growing-finishing pigs on a commercial farm in Finland, housed on partly slatted floors in 10-m2 pens of 11 pigs. The total number of pigs at the time of data collection was 780, as the farmer had removed 23 of the original pigs due to tail biting. The control pens (N = 17) had a straw rack, a metal chain and a daily provision of wood shavings. The experimental pens had the same and one of the following: the wood pens (N = 14) had horizontally suspended pieces of fresh birch wood (Ø 10 cm), 30 cm per pig; the plastic pens (N = 13) had a cross of 60-cm polythene pipes (Ø 5 cm), hanging from the ceiling; the branching-chain pens (N = 15) had two crosses of metal chains, suspended vertically; and the combination pens (N = 14) had all of the above. After 2.5 months of exposure to the objects, the pigs were video-recorded, and tail and ear damage were scored.ResultsThe pigs manipulated objects more frequently in the wood, plastic and combination treatments than in the branching-chain and control treatments (F = 7.6, df = 4, P < 0.001). The prevalence of undamaged tails was higher in the wood and combination treatments than in the controls (F = 3.0, df = 4, P < 0.05). The prevalence of undamaged ears was higher in the wood and combination treatments than in the branching-chain treatment (F = 4.4, df = 4, P < 0.01). The prevalence of mildly damaged tails was lower in the wood and combination treatments than in the plastic, branching-chain and control treatments (F = 5.0, df = 4, P < 0.01). There were no significant differences in prevalence of severely damaged tails or ears between the treatment groups. It was concluded that horizontally suspended pieces of fresh wood can increase object exploration and reduce tail and ear biting in commercial pig farming.