Biological function of valine
As lysine (Lys), threonine (THR), methionine (MET) and tryptophan (TRP), valine (VAL) is an essential and indispensable nutrient for pigs and poultry. Because animals can't synthesize Val, they must take it from the diet to meet the needs of animals, so it belongs to essential amino acids. Valine (VAL) is the fifth limiting amino acid (LAA) of pigs after tryptophan (TRP), and the fourth limiting amino acid (LAA) of broilers after tryptophan (TRP). For the minimum requirement of these animals, Val seems to be a kind of nutrient lacking substance. Now, by adding feed grade valine (VAL) to the diet, it is technically possible to prepare a diet containing six amino acids that limit animal performance.
