2 diets (18.4% crude protein) with 3.7% plasma protein or 4.9% fermented soybean meal, and 2 diets (21.2% crude protein) with 7.3% plasma protein or 9.8% fermented soybean meal. Concentrations of Lysine, Methionine, Threonine, and Tryptophan were kept consistent among diets with the same crude protein concentrations