Feed-grade amino acids
Crystalline or feed-grade amino acids are added to swine diets to reduce the addition of protein sources and offset diet costs. Feed-grade amino acids are becoming more available commercially and also increasingly cost-effective. The amount of feed-grade amino acids to use is determined by the ingredients in the diets and the stage of production, but the proper inclusion of feed-grade amino acids should not affect performance. However, it is important to ensure a sufficient supply of nitrogen for synthesis of non-essential amino acids when formulating diets with high levels of feed-grade amino acids.
Currently, feed-grade sources of amino acids are commercially available to replace lysine, methionine, threonine, tryptophan, valine, and isoleucine. The digestibility of feed-grade amino acids is usually assumed to be 100%.