Research presented at the 2016 International Pig Veterinary Society (IPVS) conference sheds new light on how pig tail biting may be prevented, while avoiding the health and welfare risks associated with tail docking.
Tail biting can occur in groups of pigs at almost any time. For reasons still not fully understood, one or more animals turn their normal exploratory behavior onto their pen-mates, repeatedly biting their tails and other body parts, causing injury and pain and introducing the threat of infection to the victim.
Once started, it is difficult to stop the tail biting, even on the best managed farms. Tail docking — removing the end portion of the piglet’s tail at around 1 week of age — is a common practice worldwide, as the shorter tail is less attractive to any potential biter. While it is generally effective, tail docking is not an ideal solution and in the EU, its routine use is banned.
Freedom from pain and injury are among the Five Freedoms that define the most fundamental features of good welfare for farm animals. It would be to everyone’s benefit — pigs, farmers, veterinarians and slaughterhouses — if tail biting could be prevented without the need to dock.
A widespread problem
Research from Ireland1,2 presented at the conference confirmed that tail biting tends to be a sporadic issue on pig farms, affecting around 2% of pigs. During the 2-year study period, around 15% of the herds were affected by some level of tail biting. Prevalence tended to be higher in the summer and autumn, pointing to more tail biting during warmer weather.
The proportion of tail-bitten pigs may increase with age. Another study from Ireland3 showed the prevalence of tail lesions increasing with age, rising from 5.4% in weaners, to 6.2% in growers and 11.0% in finishers.
The same was observed in Germany4, where there was evidence of tail biting even before weaning among undocked piglets on some farms. By the end of weaner phase, 6.3% of pigs had some minor lesions and 20% had bitten tails. Only on two of the 15 farms studied did none of the pigs have any tail injuries at the end of the growing phase.
Docking has been banned in Finland since 2003. With an average incidence of 2.3%, a recent survey5 reveals that most Finnish pig farmers do not consider tail biting to be a major problem.
Causes and correlations
Presentations at IPVS confirmed that numerous factors have been linked to tail biting in pigs.
The behavior may start very early in the pig’s life, according to an Irish study6. Researchers reported that sow age impacted the occurrence of tail lesions, with pigs from older sows (parity 6 or more) almost twice as likely to have tail lesions later in life as those from first-litter females. There was no significant difference in the rates for piglets from sows of intermediate parities. Heavier birthweights also increased the likelihood of subsequent damage to the tail.
A link between tail biting and respiratory disease was revealed by analysis of slaughterhouse data in Ireland. Pig herds with a high incidence of tail lesions also had more lung condemnations, suggesting tail biting could be linked to poor health at the herd level. However, individual sick pigs were no more or less likely to have tail injuries than their healthy pen-mates.
Monitoring activity at automatic feeders, Scandinavian researchers7 noted dips in feed intake at 2 and 10 weeks prior to an outbreak of tail biting, as well as a growth check around 9 weeks before biting episodes, indicating a possible link between feeding and the adverse behavior.
From a study of undocked pigs in Germany4, it was noted that any interruption in the supply of feed or water could initiate tail biting, and other German researchers8 observed that an episode may have been triggered by a failure of the ventilation system, which caused an 11° C rise in house temperature and an increase in the ammonia concentration in the air.
Methods of prevention
Provision of enrichment materials has been suggested as a way to minimize the risk of tail biting by pigs. The European Food Safety Authority has specified that these materials should be complex, changeable and destructible, and that objects such as metal chains and rigid plastic pipes are unsuitable as the only form of environmental enrichment for pigs.
Possible benefits of a movable straw foraging tower on tail injuries were assessed in two trials in Germany. With undocked pigs8, 25% of those with access to straw in a tower had tail lesions, compared with 80% for the group with an empty tower, although the severity of the lesions was similar for both groups. In another trial9, the incidence of tail biting was so low that researchers could not draw any conclusions on the effectiveness of the tower.
Frequent changing or re-stocking of the enrichment material was more important to distract the pigs from tail biting than the quantity of material provided, German farmers4 reported.
Treating tail biting
Treatment of tail biting is difficult once it has started. Removal of biters and/or victims from the pen is the only practical option, but producers reported in the same study that they needed additional time to observe their pigs for signs of tail biting, remove the biters and treat injured pigs.
Provision of adequate feeding space is the key to preventing tail biting, according to farmers in Finland5. They also mentioned good health, high-quality weaners and an absence of drafts in the pig pens to be important to minimize the risks.
In the longer term, breeding companies may be able to offer a solution. Topigs Norsvin has been selecting pigs on the basis of “socio-genetic” characteristics10 and breeding from pigs chosen for a low incidence of adverse traits such as aggression and tail biting. They found that the first generation of offspring were less aggressive in the finishing phase, without any unintended consequences such as a decrease in performance.
Click here to read more about changes in the pig industry, presented at the 2016 IPVS.
All papers presented at the 24th International Pig Veterinary Society, Dublin, Ireland, June 2016
- Teixeira D, et al. Tail biting is related to respiratory disease at a herd level but not at an individual level. p296
- Brush N, et al. Prevalence and trends of economically important porcine production diseases in Northern Ireland. p171
- Van Staaveren N, et al. Associations between carcass tail lesions and other welfare conditions and the performance of negative behaviors in pigs. p631
- Harlizius J, et al. A field study with undocked tails on 15 conventional farms in North Rhine Westphalia. p623
- Valros A, et al. On-farm tail-biting prevention in long-tailed pigs – results from a producer questionnaire in Finland. p144
- Calderon Diaz J, et al. Effect of sow parity and other lactation parameters on pig welfare lesions in weaner and finisher stages. p644
- Munsterhjelm C, et al. Feeding behavior and performance in relation to injurious tail biting in boars – a longitudinal study. p627
- Holling C, Grosse Beilage E. Provision of straw by a foraging tower – effect on tail biting in weaners and fattening pigs. p637
- Kalies A, et al. Efficacy of straw-filled rooting tower for prevention of tail injuries in fattening pigs. p640
- Martens M, et al. Improvement of animal welfare and productivity in pigs by using social genetic effects. p141