Group housing of sows : acquired and future research

The revised European directive (91/630) implements group housing for gilts and sows. Reports planned in 2004 and 2008 will draw up a review of studies carried out on further development of group housing systems for pregnant sows and will accompany by appropriate legislative proposals. This paper synthesises the knowledge on the functioning of social groups and its consequences on behaviour, reproductive performance and health. Attention is focused on the effect of factors linked to animal (group composition) and housing (space allowance, pen design, feeding system, enrichment design). The review points out high variation in experimental procedures and results according to combinations of housing components. The formation of stable group, a reduction of feeding competition and the provision of manipulable material are in favour of a social dynamic without detrimental effects on physical and psychological health.Nevertheless the evaluation of group housing components is still limited. Future research should be done on the pen and feeding designs limiting the social competition detrimental for reproductive performance and health. The management of enriched environment through manipulable material needs also further investigations and evaluation for the issue of sow welfare.