The effect of the level of energy intake (EI), crude protein content of the diet (CP), age and sex of growing lambs fed milk diets upon the retention of energy (ER) and nitrogen (NR) was studied.

A total of 114 lambs of the Churra breed removed from their dams at birth were used. The lambs were kept in metabolism cages and during the first two days of life were bottle-fed colostrum in quantity equivalent to 40% of their birth weight.

Afterwards milk-diets in which the protein-energy concentrations were between 15 and 35% were reconstituted at 180 g/kg of dry matter and given to the lambs according to the experimental design.