The total N excretion after feeding the low-CP diet supplemented with Ile and Val for wk 1 was reduced by 26% compared with the high-CP diet, and after wk 4 this difference was 29% reduced. When only Val was added to the diet, the wk 4 total N excretion was 35% less than the positive control. These data show that with the aid of crystalline AA, a 10% reduction in total N excretion is possible for every 1% reduction in CP content of the diet