Swine Management: Tail Biting

Tail biting is one of the most frequent problems in weaner and finisher units. We are trying to pinpoint the causes of tail biting with a view to eliminate the problem. There is constant focus on labour-saving pen types and feeding systems that at the same time increase the economic profit of each pig.

Tail biting may be caused by few or many inappropriate conditions. Sometimes, the causes are found in the housing section where the tail biting occurs, and other times in a previous housing section.

Development of program for analysis of the causes of tail biting

As part of a comprehensive research project, the Danish Applied Pig Research Scheme is co-operating with the Danish Institute of Agricultural Sciences to develop a computer program that can link behavioural observations with statistics in an attempt to find the causes of tail biting in the individual herd.

The computer program - a so-called Bayesian net - must be able to find and weigh causes of tail biting and symptoms of conditions that may lead to tail biting. Information on, for instance, the climate of the housing unit, the pigs' behaviour and the housing design is entered into the program. The program can also learn and be adjusted according to the results of changes made in the herds.

As part of the development, a prototype of the system was tested in 20 herds. In each herd, data were recorded on, for instance the pigs' behaviour and the climate in the housing unit. These data were subsequently analysed by the program, and the most plausible causes of tail biting in each herd were found.

Changes were then made in the herds to eliminate the causes, and the herds were monitored for a period of time to see whether the measures had any effect. The results are used to improve the program, and, at the same time, provide valuable knowledge of the causes of tail biting and the possibilities of eliminating them.

Temporary elimination of tail biting

Together with the Danish Institute of Agricultural Sciences, the Danish Applied Pig Research Scheme is also studying whether it is possible to temporarily eliminate tail biting. Ropes are suspended in the pens or straw or a diet with increased carbohydrate content is given for 14 days when tail biting breaks out. A temporary elimination of the problems may give the pig producers time to find the actual causes, for instance by way of using the manual or the program, and eliminate the causes altogether.

The preliminary results indicate that suspending ropes in the pens reduces tail biting when it breaks out. This is shown by the fact that the number of tail injuries was apparently reduced during the first 14 days when rope was given. The reason is probably that the wounds were allowed to heal, and that there were no new tail injuries as the pigs directed their sucking and chewing behaviour towards the rope instead of towards other pigs.

A corresponding effect was seen when giving straw. The straw was given 3-4 times a day during those 14 days. Previous studies have also shown that the allocation of straw could reduce tail biting in herds with those problems.

There has not yet been any effect in the group given the carbohydrate-rich feed.

Manual

The National Committee for Pig Production has made a interdisciplinary manual that pig producers can use as a tool for examining their herd to find the causes of tail biting. The manual consists of a checklist and a detailed description of the conditions known to cause tail biting.

The following checklist should be used if there is tail biting in the herd. Further recommendations and explanations of the points can be found in the manual concerning tail biting.

Quick intervention in case of outbreaks of tail biting 

Water supply 

Feed 

Pen design 

Stocking density and number of feeding points 

Transfer strategy and sorting 

Rooting and enrichment material 

Potential equalisation 

Regulation of temperature, climate and air quality