Although there is some understanding of the effects of immediate levels of nutrition on ovulation rate and embryo wastage, it is not yet possible to predict the reproductive performance of ewes at pasture in the autumn. In many situations sward height declines over the pre- and post-mating period but herbage intake and reproductive performance under these circumstances have not been described. Furthermore, responses in reproductive performance to supplementary feeding at pasture in the autumn have been variable. It may he possible to explain some of this variation in terms of sward height and the substitution rate of herbage by the supplement. This paper reports 2 experiments which were conducted to describe (1) the herbage intake by ewes grazing swards at different heights and when supplements were offered, and (2) the reproductive performance of ewes given supplements as sward height declined.