For a long time, the imbalance of microbial carbon distribution has hindered the accumulation of natural metabolites. Among them, feed grade L-Threonine is an important amino acid, no matter for livestock or the ones who raise livestock. L-Threonine cannot be synthesized in livestock bodies and must be supplied through feed. Therefore, adding an appropriate amount of L-Threonine crystal to the daily feed has become more and more important.