Essential and non-essential amino acids
The 20 amino acids that make up proteins are conventionally classified as essential or non-essential. Essential or indispensable amino acids are not synthesized by the pig and must be supplied in the diet, whereas non-essential or dispensable amino acids are synthesized by the pig using nitrogen provided by proteins in the diet. Some amino acids are conditionally essential, amino acids with greater demand than synthesis under some conditions, i.e. depending on stage of growth, productive function, or dietary composition.
The 10 essential amino acids for pigs are: lysine, methionine, tryptophan, threonine, valine, isoleucine, leucine, histidine and phenylalanine. Dietary supply of protein must be sufficient to provide all the essential amino acids and the nitrogen required for synthesis of non-essential amino acids.