Effects Of Mixing Ratio And Bioenzymes On The Storage Quality And Microbial Community Of Grain Stillage And Wheat Bran

The utilization rate of agricultural by-products is 40% in China,far less than developed countries(90%),causing a lot of resources wasted,and even pollutes the environment.On the other hand,due to the rapid development of animal husbandry,the demand for feed quantity is increasing,resulting in such problems as shortage of feed resources,competition between human and livestock for grain and so on.A lot of grain stillage were produced every year in China,but the utilization rate is low.The starch,protein and other substances of grain stillage are conducive to providing energy for fermentation.But grain stillage also have high moisture content and low acidity.If grain stillage are not utilized in time,can easy to decay and deteriorate.On the other hand,comprehensive utilization rate of wheat bran is less than20%,it was mainly used for animal feed,moisture content was low.Therefore,in order to improve the utilization of grain stillage and wheat bran,the shortage of feed resources and competition between human and animal for grain,fermented feed was prepared with grain stillage and wheat bran as experimental raw materials.Grain stillage and wheat bran were mixed according to different mixing ratios of 4:6?6:4?8:2?10:0.Four treatment groups were set up for each mixing ratio,non-additive control group(group CK),cellulase additive group(group C),xylanase additive group(group X)and compound enzyme additive group(group CX,cellulase + xylanase),stored at room temperature for 60 d,and the chemical composition,fermentation quality and microbial community diversity were observed.The main results are as follows:1.Comparing the sensory evaluation results of four treatment groups at different mixing ratio,it was found that no decay were occurred in the four treatment groups during silage.But the sensory quality was poor at 10:0 mixing ratio,and the loss of dry matter was high(2%).2.The chemical results showed that the contents of WSC(Water soluble carbohydrate),ST(Starch)and CP(Crude protein)in the four treatments were decreased with the storage time prolonged,but increased significantly after storage for 60 d(P<0.05).The contents of WSC and CP in group C,X and CX were increased at four mixing ratio in different extent,and the contents of WSC,ST and CP in group CX were higher than those in group C and X at8:2 mixing ratio.On the other hand,the ADL(Acid detergent lignin)content of group CX decreased significantly from 18.20% in 0 d to 9.20% in 60 d(P<0.05),while the other treatments reduced less than 8%.However,the contents of NDF(Neutral detergent fiber)and ADF(Acid detergent fiber)in C,X and CX groups were not decrease significantly during storage(P>0.05).3.The fermentation characteristics showed that the pH values of the four treatments decreased significantly with the increase of grain stillage(P<0.05).When the mixing ratio was 6:4 and 8:2,the pH values of the four treatments were in the good range of semi-drysilage(3.7~4.8),and group C,X and CX were further reduced the pH value,and the effect of group CX on reducing pH values was better than that of group C and X.On the other hand,the LA(Lactic acid)content of each group increased with the increase of grain stillage,the LA content and LA/AA(ratio of lactic acid to acetic acid)values of group C,X and CX were increased significantly when the mixing ratio was 4:6 and 6:4(P<0.05).Besides individual groups,the LA/AA values were higher than 3,which belonged to homozygous fermentation and benefits to the preservation of energy substances.4.The results of bacterial community showed that during the storage process the relative abundance of dominant bacteria Firmicutes in phylum level and the dominant bacteria Staphylococcus and Lactobacillus in genus level were both increased with the increase of grain stillage.On the other hand,group C,X and CX was significantly increased the relative abundance of Staphylococcus and Lactobacillus,especially group CX of 8:2 mixing ratio.5.The results of fungal community showed that the dominant fungi in phylum level were Ascomycota,in genus level were Pichia,Alternaria and Aspergillus,and the relative abundance of Aspergillus was significantly reduced in the group C,X,CX when mixing ratio were 6:4 and 8:2.6.The correlation heat map of bacteria and fungi showed that the organic components DM(Dry matter),CP and fiber components NDF,HC(Hemicellulose),HoC(Holocellulose)and fermentation characteristics of FA(Formic Acid)were positively correlated with Staphylococcus,Pantoea,Cetobacum and Plesiomonas,and negative correlation with Propionibacterium,Acetobacter and Bacillus.The content of NDF were positively correlated with Xeromyces and Pichia,while Lasiodiplodia,Verticillium and Malassezia were negatively correlated with the content of pH,CP and HoC.Through the comprehensive analysis of sensory quality,chemical components,fermentation characteristics and microbial community showed that the quality of silage was better in 6:4 and 8:2 mixing ratio,and the effect of mixed enzyme group(group CX)on fermentation quality was better than the group of add cellulase or xylanase separately.