L-threonine is an essential amino acid for animals. It can be used for the sedimentation of protein, participate in animal¡¥s supersession and maintaining activities to enhance the digestion and immunocompetence of the animal. It can also adjust the balance of the amino acids in feed, enhance the efficiency of feed utilization, and lower the cost of the feed when work with other amino acids. Description: white or sandy beige ctystal or powder Assay/%: y98.5 Loss on drying/%: ¨¹1.0 Residue on ignition/%: ¨¹0.5 Heavy metal (pb)/(mg/kg): ¨¹20 package: 25kg paper bag/pp woven bag Arsenic(as)/(mg/kg): ¨¹2.0 storage: cool dry and good ventilation