The effect of intake level during the milk-feeding period and dietary protein content during the post-weaning period on performance, weight of components of the digestive tract and carcass and non-carcass chemical composition was investigated in 28 Churra lambs. A 2 × 2 factorial design was used with two intake levels during the milk-feeding period (Lmilk: 0·9 and Hmilk: 1·5 MJ gross energy per kg M0·75 daily) and two concentrate supplements (Lprotein:barley grain and Hprotein: barley grain plus 200 g/kg fish meal) during the post-weaningperiod. After selecting an initial slaughter group of four 2-day-old lambs, 12 lambs were assigned randomly to each of two intake levels during a 4-week milk-feeding period and given food individually. Four lambs from each intake level were slaughtered at weaning (30 days old) and the remaining 16 were weaned between 30 and 49 days old (weaning period). Eight lambs from each nutritional regimen during the milk-feeding period were further divided into two equal groups and given food individually ad libitum with hay and the post-weaning concentrate, according to the experimental design until thefinal slaughter weight (20 kg) (post-weaning period). Lmitk lambs showed a capacity to grow as well as the Hmilk during the weaning and post-weaning period and there were no differences (P > 0·05) in dry-matter intake and food conversion ratio among treatments. Before weaning, the weight of the reticulo-rumen was not affected by the intake level during the milk-feeding period. The most affected component of the gastrointestinal tract was the small intestine as proportion of the digestive tract which was lower in Lmilk lambs (P < 0·05). At 20 kg live weight, the relative size of the reticulo-rumen was greater (P < 0·01) and the abomasum (P < 0·05) and large intestine (P < 0·01) were smaller in lambs which were given the Hprotein concentrate after weaning. The organic matter apparent digestibility (OMD, P < 0·05) and crude protein apparent digestibility (CPD, P < 0·05) of the post-weaning diets was greater in Lmilk lambs and the Hprotein post-weaning diet was associated with a greater dry-matter apparent digestibility, OMD and CPD when lambs were close to final slaughter weight. At 20 kg live weight, the proportion of protein in the carcass of Lmilk lambs was greater (P < 0·05) than in Hmilk lambs. The greater growth of the reticulo-rumen of the Lmilk lambs might have increased solid food intake after the milk-feeding period, led to greater CPD of post-weaning diets and had consequences in terms of carcass composition.