L-lysine is one of the eight essential amino acids. Nutritionists consider it as amino acid of the most lack and the most limiting amino acid of plant protein. L-lysine is used for dietary supplement: e.g. if lack of L-lysine will cause protein functioning holdback and growing holdback. L-lysine is widely used in industry of foodstuff, pharmaceutical and feed. In the industry of feed, it is used for feed of pig and birds. The normal dosage in feed additives is 0.1%-0.3%. When adding corresponding quantity L-lysine into feed, not only the livestocks and birds would grow fast, but also the dosage of rude protein in feed would be reduced 3%-4%.