Abstract
Summary. The effect of dietary restriction on the oestrous cycle of Wistar strain rats was modified by the presence of the male. In the absence of the male, increasing irregularity of oestrous cycle with a significant lengthening of the cycle (P<0·01) was observed with increase in the degree of inanition. The presence of the male had a significant effect (P<0·01) on the cyclic behaviour of rats on the lowest planes of feeding, bringing these animals into oestrus earlier than expected.