Twenty pregnant Merino ewes grazed a ryegrass pasture and were offered either no supplement or 500 g/head/day of a concentrate supplement from days 30 to 90 of pregnancy. After that date, all ewes were supplemented. Maternal carcass and „non-carcass" components, uterine walls, foetus and placentas plus cotyledons were chemically analysed. At day 90, there was no significant difference between supplemented and non-supplemented animals in the mobilization of body reserves. However, from day 91 to 140, a significant effect of the previous nutritional regime was observed. Body condition score on day 30 accounted for most of the fat mobilization from days 30 to 90. Nevertheless, these mobilizations were not reflected in any significant difference in the birthweight and chemical composition of the foetus. Merino grazing sheep hence are able to compensate for feed restriction during mid-pregnancy, through the mobilization of body reserves, avoiding any influence on the foetus.