Effects Of Enzymes And Its Added Levels On Quality Of Rice Straw Silages

In order to examine the effects of moisture contents and additives on the silage fermentationof rice straw and provide a solid theoretical foundation for making high quality silage of rice straw,the effects of moisture contents (70.0%-MC1and37.5%-MC2) and additives (cellulase,xylanase and their mixture) on the fermentation quality and chemical composition of rice strawsilage were investigated in three laboratory-scale experiments.In experiment1, MC1and MC2rice straw were treated with cellulase (CEL) at the rates of0mg.kg-1(CON),20mg..kg~-1(CEL1),40mg.kg~-1(CEL2) and80mg.kg~-1(CEL3) fresh straw atensiling. In experiment2, MC1and MC2rice straw were treated with xylanase (XYL) at the ratesof0mg.kg-1(CON),20mg.kg~-1(XYL1),40mg.kg~-1(XYL2) and80mg.kg-1(XYL3) fresh strawat ensiling. In experiment3, MC1and MC2rice straw were treated with Enzyme mixture(MIX) atthe rates of0mg.kg~-1(CON),25mg.kg~-1(MIX1),50mg.kg~-1(MIX2) and100mg.kg-1(MIX3)fresh straw at ensiling. After application of the treatments, the material was thoroughly blended byhand and500g of the treated rice straw was packed into a bottle (1liter capacity), each treatmentwas made in triplicates. The bottles were sealed and stored at ambient temperature. After ensilingfor60d, the bottles were opened. The fermentation characteristics were evaluated by subjectivequality, chemical composition, organic acids and pH value.The results showed that three additives significantly decreased the contents of neutraldetergent fiber (NDF), acid detergent fiber (ADF) and NH3-N and pH value, significantlyincreased water soluble carbohydrate (WSC) content and dry matter recovery (DMR) comparedwith the controls of MC1and MC2silages. Moisture contents had marked effect on thefermentation quality of silages. In experiment1, there were lower pH value and higher lactic acidcontent in MC1silages than in MC2silages, while there were lower NH3-N content and higherDMR in MC2silages than in MC1silages. CEL2had the most extensive fermentation both inMC1and MC2, manifested by the lowest pH value and gas loss rate (GLR) and the highest lacticacid content in MC1and lowest NH3-N in MC2., In experiment2and3, the silage fermentationquality of MC2was better than that of MC1. There were lower pH value and higher WSC contentin MC1silages than in MC2silages, while there was higher DMR in MC2silages than in MC1silages. XYL3treateed silage had the lowest pH value, lowest contents of NDF, ADF, hemi-cellu- lose (HC), NH3-N and GLR, and highest contents of lactic acid and WSC in MC1silages, andhighest DMR in MC2silages. MIX3treated silage had the lowest pH value and lowest contents ofNDF, ADF and GLR, and the highest contents of lactic acid and WSC in MC1silages, and thelowest contents of propionic acid, butyric acid, HC and NH3-N in MC2silages.