Tail Biting - Pinpointing the causes

By The National Committee for Pig Production, Annual Report 2004, Denmark and published by NCSU Swine Extension - 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.
calendar icon 18 July 2005
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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.


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 at www.lu.dk.

  • Quick intervention in case of outbreaks of tail biting
    • Have steps been taken to eliminate tail biting quickly?
    • Are tail-bitten pigs treated correctly?
  • Water supply
    • Are the nipple drinkers supplying the correct amount of water?
    • Is there a sufficient number of drinkers in each pen?
  • Feed
    • Does feed mixed on-farm segregate?
    • Is the colour of the manure in pens the same at both ends of the pipeline?
    • Is the pigs’ behaviour the same at each delivery of finished feed or of premix for feed mixed on-farm?
  • Pen design
    • Is the pen designed correctly with a lying area, an activity area and a dunging area?
  • Stocking density and number of feeding points
    • Are the space requirements met, so that overcrowding is avoided?
    • Are there enough feeding points compared with the number of pigs?
  • Transfer strategy and sorting
    • Is mixing of pigs between pens after transfer avoided?
  • Rooting and enrichment material
    • Do the pigs have permanent access to enrichment and rooting materials?
    • Is the material placed correctly?
  • Potential equalisation
    • Are the electrical installations in the housing unit at the electric switchboard main-equalized and connected to an earth rod?
    • Are the electric wirings in the housing unit equalised?
  • Regulation of temperature, climate and air quality
    • Does the housing temperature correspond to the age of the pigs and the design of the housing unit?
    • Is the pigs’ lying behaviour normal?
    • Does the air in the housing unit feel good?
    • Does the ventilation system work satisfactorily?
    • Are the pigs dunging where they are supposed to?
    • Is the bedding dry?
    • Are the slurry containers emptied?
Reproduced Courtesy

Source: North Carolina State University Swine Extension - March 2005
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