Searching for solutions to pig tail biting

Damian McCarney 

To the uninitiated, pigs biting the tails of other pigs may sound quite frivolous, but it’s actually a serious issue facing many pig farmers. What sparks it, how to stop it once an outbreak has occurred and how to prevent a future one remains unclear, but a team in Teagasc are trying to get to the bottom of the harmful behaviour.
“It has serious consequences,” insists Dr Amy Haigh, who discussed farmers’ experiences of tail biting at a recent symposium and trade fair in Mullingar.
“Not only from a welfare point of view for the pigs involved, but it also causes a huge economic problem for the farmer.”
Amy is concluding her one year post doc project with the ‘Entail’ project, in which she focused on the use of compressed straw within a slatted system. This ties in with the wider research work of PhD student Jen-Yun Chou who is investigating environmental enrichment and management strategies for pigs managed on slatted floors.
“Trying to resolve the issue is also very labour intensive,” she adds. “If one starts biting, the initial biter may not be the one that continues it; others may start biting.
Generally if you have a biting outbreak you’ll have a number of victims and one of the main solutions is that farmers separate them, but obviously space is often in very short supply.”
A farmer having gone through the time consuming process of isolating and treating pigs may still face a problem when he brings his stock to the abattoir.
“It may have been bitten when it was initially weaned (within the first two months), the wound could heal but it could become infectious and form lesions, which aren’t seen, but could form down the spine, and lead to the meat being condemned.”
Amy notes that given the cost of feeding the pig to the stage where it is ready for the factory means the farmer could accrue significant losses.
“Also, once a pig has been bitten, a lot of the time they find that they grow a lot less as well.
They don’t do as well, so you could have pigs taking much longer to get to a finishing stage.”

Outbreak
One biting pig can reportedly lead to an outbreak within a pen. The Celt wonders if this is a case of pigs fighting back, or simply a learned behaviour?
“A pig’s snout is a real sensory organ for them. They would use their snout the way that we would use our hand so if they are in a pen and they are in a lot of contact with other pigs it can even start as play behaviour.
“Also there have been some reports of it occurring when the pigs are at the feeder and maybe some of the smaller ones are not getting access, so they are frustrated that they can’t get at food, and so they may bite the tails of the more dominant pigs at the feeder.
“Some people have felt that once there’s blood, pigs will be attracted to that, and messing with it, making it worse from that point of view.”

Frustrating
There doesn’t seem to be any hard and fast rules on what sparks tail biting, which Amy notes is why it is “so frustrating for farmers”.
“One factor could cause it on one occasion and another factor could cause it on another occasion. So a farmer might not have a case for months or years and then suddenly they will have a massive outbreak in one batch of pigs. It’s very hard to pin point what the factors could be, but it seems that everything is a fine balance.”

Stocking levels and ventilation appear to be amongst the many factors at play, but Amy notes it seems to vary on a farm to farm basis.
“Some would find that changes in temperature would be big a factor, some would find certain breeds would be vulnerable. One of the most frustrating things for farmers is that there is no real way of predicting when it’s going to occur, and there’s no real solution when it does.
“Certainly from talking to farmers, one of the things that they felt was important was the stocking - particularly if they didn’t move the pigs to the next stage, to a bigger pen soon enough - in that week they would have an outbreak of biting. Other things would be pigs in poor health, some of the weaker smaller pigs would be the biters, again... not being able to get to the feeders.
“Food as well, a lot of farmers have found that maybe changes in diet caused it,” she said, adding that this was also a factor discovered by a study in Finland.

Stimulus
Given that pigs are regarded as very intelligent, is there any indication that lack of stimulus is a factor?
“I would imagine it would be a huge factor, yes.”
“Space is so restricted that there’s not even that much space to move around without bumping into another pig. Generally if a pig was out it would spend up to 60% of its day foraging - foraging is such a natural thing for a pig to do, so even though they have been domesticated for hundreds of years, they haven’t lost that ability, and that want to forage.” Research has shown that approximately 65% of farmers respond to an outbreak by adding extra enrichment - metal chains, or commercial toys suspended from the ceiling for them to chew.
“Another thing that pigs really favour is novelty - so they will get bored of the same enrichment all of the time... and spend less time interacting with it. “Also a lot of times only one or two things will be put in. If you have a pen of 50 pigs, they are not all going to get access to it at the same time. It is a legal requirement now for pigs to have enrichment.”
Amy says that there have been reports of pigs reared in a non-commercial environment engaging in tail biting, but to a “very minor” degree in comparison.
“You wouldn’t notice it the same extent because obviously they are going to have much more room to move around and be more stimulated.
“Also probably they are not as vulnerable to extremes in their environment either. Because obviously the ones that are intensively farmed are kept at the same temperature all of the time and everything is very regulated, whereas if they are outside they would probably be a bit more hardy to the elements and not as vulnerable to extremes to the same degree.”

Breakthrough
Does Amy expect a breakthrough from the Teagasc study?
“It’s very hard to say, the main aims of our project is to identify enrichment that will can actually be used by farmers, because it will be compatible with the slatted systems, that will occupy the pigs, that it will meet their requirements and also reduce these abnormal behaviours such as tail biting. “We look at behaviour, we look at the stress levels of the pig with different treatments.
“We look for tail lesions and ear biting behaviour every two weeks, and follow them right through to the end and then we look at the reports from the abattoirs to see if any were condemned and then we can identify what was the most efficient enrichment.”