Study Of Processing Technology Of Spent Mushroom Substrate For Feeds Production

Mulberry branch is one of the by-products of seri-cultural production. At present, cultivating edible mushroom is the main way of high-value utilization of it.Mulberry branch is rich in nutrients and antioxidants. Spent mushroom substrate contains various beneficial nutrients as well. Meanwhile, there are many impurities which are difficult to be used also in the spent mushroom substrate. So that, removing impurities of spent mushroom substrate has been the key point to enhance its value. In this thesis, spent mushroom substrate was studied as a potential nutrient source for feeding broiler. The nutrient content of several spent mushroom substrates were determined. Several pretreatments including dilute sulfuric acid, sodium hydroxide, enzymatic hydrolysis and fermentation were compared to determine the optimal method for degrading cellulose to produce reducing sugars. Then, the feed was produced and the breeding effect was determined. The results are as follows.1.Analyzed nutrient content of five spent mushroom substrates which cultivated with mulberry branch. Five kinds of spent mushroom substrates were selected as the research object. The nutrient contents including crude protein, crude cellulose, amino acid, reducing sugar, crude fat, Ca and P were determined. Results showed that there were obvious difference among the different kinds of spent mushroom substrates. The crude protein content of panus giganteus and pleurotus geesteranus, with values of 9.64% and 8.99%,were more than others. And their crude cellulose content were less than others with values of 19.97% and 23.44%. But there were still obvious different between the chaffs and commercial feed. Therefore, it is necessary to improve the nutrients of spent mushroom substrates.2.Optimized the process of hydrolysis and enzymatic hydrolysis. Severalpretreatments were compared to determine the optimal method for degrading cellulose to produce reducing sugars. The results showed that the optimal condition of alkali hydrolysis was: hydrolysis time of 90 min, alkali concentration of 1 M, solid to liquid ratio of 1:6 and hydrolysis temperature of 80 ?, the total amount of reducing sugars reached 13.91%, and the cellulose degradation rate was 42.75%. The optimal condition of acid hydrolysis was:hydrolysis time of 120 min, acid concentration of 3%, solid to liquid ratio of 1:17 and hydrolysis temperature of 120 ?, the total amount of reducing sugars reached 12.95%, and the cellulose degradation rate was 38.86%. Although the alkali hydrolysis provided higher reducing sugar yield, it is instability and it provided lower recovery rate of chaff. So that,acid hydrolysis was selected as the optimal pretreatment method. Followed, the optimal condition of enzymatic hydrolysis was: hydrolysis time of 48 h, liquid to solid ratio of 2:1,hydrolysis temperature of 40 ?, p H of 4.8, cellulose to xylanase ratio of 7:3 and enzyme loading of 200 IU/g, the cellulose degradation rate was 38.2%.3.Screened the optimum strain for fermentation. Based on the pretreatment, the spent mushroom substrates were mixed with rice bran, wheat bran and corn flour to fermentation. Four strains of fungi, Aspergillus niger, lactobacillus, Saccharomyces cerevisiae and Candida tropicalis, were compared to screen the optimum strain for fermentation. The influence of 4 strains on nutrition of spent mushroom substrates during the fermentation process was studied. Results showed that the highest cellulose degradation was obtained using Aspergillus niger fermentation for 60 h.4.Feeding experiment with broiler. The results showed that fermented spent mushroom substrates did not make broiler death or disability. The addition of fermented spent mushroom substrates from 2% to 10% has little influence on the quality of feed. The addition of 8% fermented spent mushroom substrates could improve palatability of the feed.At the same time, it made broiler grow faster. In this study, it was found that addition of the fermented chaff with 6% and 8% could improve broiler's meat performance, suitability,immune performance and antioxidant capacity. So that, added fermented spent mushroom substrates into broiler's diet with addition from 6% to 8% will get the best production efficiency.