L-Tryptophan is considered as an essential amino acid in diverse species.
It is the 3rd limiting amino acid in swine feed and the 5th limiting amino acid in aqua feed.
Also, in layers, it can be considered as the 4th limiting amino acid.
(The order of limiting amino acids can differ depending on environment or feed ingredients.)
![](https://www.cjbio.net/res/images/sub/tryptophan/img_amino_acids.png)
Functions ofL-tryptophan
L-Tryptophan is needed to maintain amino acid balance, ensure normal growth and enhance antibody
development. Also, it is the precursor of serotonin/melatonin which has a calming effect that can be well
measured in optimized daily weight gain and feed efficiency. What’s more, metabolites from
kynurenine pathway such as niacin can regulate the immune system resulted in health maintenance.