Abstract: According to the method of the national feed hygienic standards, the experiment detected and safetly evaluated the different growth stages of Pleurotus ostreatus medium matrix component.In order to evaluate the feed value of the Pleurotus ostreatus and realize reasonable utilization of spent mushroom substrate(SMS) resources by detecting on the nutrient components of spent mushroom substrate after different harvest times,we found that the fourth harvest of SMS used as feed had a higher nutrition value and lower production cost. The crude protein content was 10.10% at this moment. Compared with original substrate,the crude protein content was increased by 59.31%,crude fiber content was reduced by 29.57%,and the degradation rate of ligin, hemicellulose and cellulose were increased by 63.62%, 46.60% and 77.06%. Based on the national feed hygiene standards,the content of free gossypol, aflatoxin B₁ and heavy metal in SMS (the fourth harvest) were measured. The results showed that the free gossypol content was only 67.90 mg/kg,aflatoxin B₁ was not detected (＜10 μg/kg).And the content of lead,fluorine,chromium,cadmium and mercury all met the national feed hygiene standards. So it was feasible to use SMS(the fourth harvest) as a new non-conventional roughage resource for ruminants.

Key words: Pleurotus ostreatus; spent mushroom substrate; nutrition; feed value; analysis