Science - January 6, 2010

With their tail between their legs

Pig tails reveal outbreak of tail biting. Pig farmers can take preventive action.

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If pigs walk around with their tail between their legs they often become the victims of tail biting. It is therefore possible for alert pig farmers to take preventive measures to avoid tail biting. These are the findings of a study by Johan Zonderland, published last month in Applied Animal Behaviour Science.
Zonderland observed nearly one thousand weaned pigs - pigs of four to ten weeks old that have just been separated from the sow. He recorded the position of the pig tails that had not been docked. Zonderland noticed that the tails were curled, pointed straight backwards, were wagging or were stuck between the hind legs. 'In our previous study we had already noticed that pigs with curly tails virtually never had any damage. But there was always something with pigs with their tails between their legs.' He has now quantified that observation. A quarter of the pigs seen to have their tails between their legs in two observations had serious wounds on their tails three days later. Bite marks from other pigs were found on 32 per cent of these pigs. 'With their tail between their legs' therefore heralds tail biting. 'Pigs already have the potential to bite, only you don't yet see the effect on their tails', says Zonderland.
In this way pig farmers can recognize and prevent an outbreak of tail biting. Even throwing handfuls of straw or a toy into the group of pigs twice a day can make a big difference, another of his studies showed. 'It is much more difficult to stop the tail biting once the tails are wounded and there is blood on them.' A precondition is that the pig farmer needs to walk attentively through the pig shed at regular intervals, surveying the pigs' behaviour and the position of their tails. 
The researcher admits that this is not easy if you have three thousand pigs in your pig sheds. But there is no alternative as he has not yet found a generally applicable cause of tail biting. 'Every pigsty has its own story.'

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