Ad libitum feeding of a high fibre diet may be instrumental in reducing the development of abnormal behaviours in group housed sows (Brouns et al.1994). However, although there may be welfare benefits associated with feeding sows in this way, such a feeding practice is unlikely to be adopted unless it is commercially viable. This study compared the reproductive performance of gilts fed a high fibre diet ad libitum throughout gestation, with gilts fed a commercial diet on a restricted level.