Individual pig-related factors

International audience

anglais. The suffering of tail damage and the expression of behaviours associated with tail biting are influenced by factors inherent to the pig itself. When the influence of environmental, nutritional and pig-related factors is high, manipulative behaviour on group mates may evolve into an outbreak of detrimental behaviour. Individual pig-related factors, including sex type, growth, susceptibility to stress, microbiota composition and health, are often studied – indeed, increasingly so. Some are expected to be more significant than others, and studies accounting for several of these factors at a time should be undertaken. In this chapter, we will describe the internal factors that explain why pigs move from normal behaviour to this abnormal behaviour towards conspecific group members. We emphasise genetic factors in tail biting associated behaviours. Both direct and indirect effects determine an animals potential to tail bite or to be tail bitten, and they are expressed by each pig. Indirect effects refer to a pig’s influence on the tail biting associated behaviours of other pigs it is housed with. The performance of tail biting associated behaviours also relates to previous experience within the group, and to previous developmental stages, with strong effects suspected to be present in the early developmental phase, notably exposure to stress. Epigenetics therefore undoubtedly has a role to play here. Progress needs to be made on the characterisation of animals, including measuring their behaviour over the long term so that sporadic events of tail biting are captured. Relevant analytical models for this are available. The continuous recording of animal and environmental data (incl. social context), and the development of integrated analyses of large populations accounting for internal factors are essential if we are to find solutions that reduce the prevalence of tail biting in pigs.