The need to continuously re-establish the social structure in dynamic groups of sows gives rise to higher levels of aggression compared to stable groups. Previous familiarity of animals could shorten the time it takes to reorganise the social structure, but relies on the animal's social memory.

In intensive farming, it is Important to remember that each individual animal has its own needs (Hughes and Duncan, 1988). In pigs, close confinement and food restriction can result in the development of abnormal behaviour. Terlouw et al. (1990) suggest that an individual's temperament may influence the development of such behaviour and therefore how a pig copes with environmental stress. Individual differences in behaviour are consistent and measurable (e.g. Lyons et al.. 1988). By determining an animal's temperament using a characteristic profile, it may it may be possible to predict the response of a temperament “type” to certain conditions.This study is part of a larger project concerned with the effects of housing and feed level on the development of behaviours in group-housed gilts. All the pigs entered a series of tests to measure individual characteristics prior to the main experiment. Two of the tests, one measuring feeding motivation and the other social behaviour, are compared here.