The effect of body condition at weaning and its subsequent variation on the resumption of oestrus activity was studied in thirty-seven Rasa Aragonesa ewes lambing in the anoestrus season (May 7th-14th). The ewes were kept in individual cages during the experiment period and were distributed in two groups according to their body condition score (BCS greater than or equal to 2.5 and less than or equal to 2.25). Ewes were given ad libitum 3 per cent ammonia treated barley straw, supplemented with either 500 or 250 g/d of concentrate. Digestible organic matter intake (DOMI) was higher in ewes receiving 500 g/d of concentrate and in those with a lower BCS at weaning. Changes in body energy, estimated from the dilution space of deuterium oxide, were better correlated (r