DL-Methionine(feed grade) is one of the 13 essential amino acids in animal's body, which is lacking in feed and cannot be synthetized in layer's body. So it must be added as feed additive in feed. If the content of DL-Methionine is insufficient, the nutrition in feed cannot be fully absorbed, and furtherly, influence the egg weight. If DL-Methionine is seriously inadequate, not only will affect laying rate, but also threat to life. So we must control the using quantity.