Nowadays, most of the world's pig farms use corn-soybean meal diets. For corn soybean meal diets and pigs' amino acid requirements, lysine and methionine are the first and second restrictions for pigs. Amino acids, so often have to add extra.
The essential amino acids for pigs include lysine, methionine, tryptophan, phenylalanine, leucine, isoleucine, valine, and threonine. Soybean meal is rich in lysine and tryptophan, and corn contains more methionine, so corn and soybean meal with amino acids complement each other to achieve a better nutritional balance.
Because of the lack of essential amino acids, the synthesis of protein in the body is reduced, resulting in a series of in vivo protein metabolism, related enzyme synthesis problems, the most important manifestation of growth retardation, and even trigger metabolic diseases.
Lysine is mainly used for protein deposition and is rarely involved in metabolic processes. The role of methionine is more complex, in addition to deposition of protein, but also closely related to the metabolism of sulfur compounds in vivo, in addition to its use of methyl, toxic or drug methylation and play a role in detoxification.