The energy contents of the high and low lysine diets were set according to standard industry practice (14.5 and 13.5 MJ digestible energy (DE)/kg, respectively). All diets were created by blending the high and low lysine diets in the appropriate ratios for the lysine requirement relative to weight (Table 1). The diet for the single treatment comprised 45% of the high lysine diet and 55% of the low lysine diet and was 13.9 MJ DE/kg and 0.65 g SID lysine/MJ DE. The energy and SID lysine contents of the blend diets were gradually decreased on a weekly basis from 14.5 MJ/kg and 0.84 g SID lysine/MJ DE to 13.5 MJ/kg and 0.49 g SID/MJ DE.