Tell Tail Signs: imaging technology detects early warning signs of tail biting in pigs
The challenge: predicting the unpredictable
One of the many challenges associated with tail biting behaviour is that outbreaks appear to be unpredictable, often starting without any apparent cause. Tail docking of piglets before seven days of age is one method widely used to reduce the risk of tail biting later in life, however this practice should be thought of as a last resort after other risk factors for tail biting have been improved, such as providing enough space and enrichment. Tail docking is an undesirable mutilation; it is known to be painful for piglets and does not completely eliminate tail biting. Routine tail docking has not been permitted in the EU for over 25 years, with the original directive on pig welfare (Directive 91/630/EEC) amended in 1994 to include this regulation and subsequent updates reinterating that there should be no routine docking (Council Directive 2008/120/EC). Despite these regulations over 70% of pigs in the EU are tail docked. Farmers are reluctant to risk leaving tails intact, partly because of the unpredictable nature of a tail biting outbreak. However recent research shows that there are behavioural changes in pigs before a damaging tail biting outbreak starts.
What are the early warning signs of tail biting?
There have been various studies examining the behaviour of pigs in the lead up to a tail biting outbreak. Increased activity, increased object and tail-directed behaviours and lowered tail posture are all behavioural signs observed before an outbreak. Our research at SRUC focussed on changes in tail posture as a promising indicator to investigate further. We video recorded grower pigs 24h a day throughout the weaner-grower period to continuously observe changes in their tail posture. 23 different groups (approximately 27 pigs per group) were raised with intact tails under intensive conditions. There were 15 groups where tail biting outbreaks occurred, and 8 with no outbreaks. Outbreak groups had altered tail posture, with fewer curled tails and more lowered and tucked tails compared to non-outbreak (control) groups. There were significant changes in tail posture in the week before an outbreak with outbreak groups changing from 15% tucked tails seven days pre-outbreak to 20-25% tucked tails one day pre-outbreak. This showed that tail posture has the potential to be used as an early warning indicator of a tail biting outbreak, but how easy is it to observe on farm?