The experimental diets fed as crumbles or pellets varied in energy; protein ratio by 9 and 18% from basal values within both low and high nutrient density series. The energy ; protein ratio of the basal diet was increased from 10.75 to 11.4 kcal ( 45.1 to 47.4 kJ ) TME/g protein at 3 weeks of age. Crude protein and energy ; protein ratios of the basal diets are shown in Table 1. Composition of the basal diets of both nutrient density values were originally calculated using apparent metabolizable energy ( AME ) values but have now been recalculated using true metabolizable energy ( TME ) values determined by the procedure of Sibbald (1976) on feedstuffs in use at this station. Differences in relative energy value between the TME