| Although rice straw and Chinese cabbage waste are agricultural by-products,they also have nutritional value.The mixed silage of rice straw and Chinese cabbage waste can not only make the two agricultural by-products form complementary nutrients,but also improve the utilization rate of agricultural by-products to a certain extent.Therefore,this paper mainly studies the effects of different treatments on the nutrient and quality of the mixed silage of rice straw and Chinese cabbage waste,analysis of dominant bacterial and fungal flora of mixed silage microbial population.In order to select the best silage combination,the feeding value of the group with better silage effect was evaluated by simulated fermentation in vitro.Experiment 1:Effects of different treatments on nutrients and quality of mixed silage of rice straw and chinese cabbage wasteThe purpose of this experiment was to explore the effects of different ratio of rice straw to Chinese cabbage waste,different amount of Lactobacillus plantarum and cellulase on the nutrient and quality of mixed silage.Using rice straw and Chinese cabbage waste as silage materials and L9(33)three factors and three levels of orthogonal experiment design,the ratio of rice straw to chinese cabbage waste,the amount of Lactobacillus plantarum and cellulase were designed according to three different gradients respectively,and set up the control group,a total of 10 experimental groups,each group was set up with three repetitions.0.030 g/kg Lactobacillus plantarum+0.20 g/kg cellulase(group 1),0.035 g/kg Lactobacillus plantarum+0.25 g/kg cellulase(group 2),0.040 g/kg Lactobacillus plantarum+0.30 g/kg cellulase(group 3)were added respectively when the ratio of rice straw to Chinese cabbage waste was 4:6.0.030 g/kg Lactobacillus plantarum+0.25 g/kg cellulase(group 4),0.035 g/kg Lactobacillus plantarum+0.30 g/kg cellulase(group 5),0.040 g/kg Lactobacillus plantarum+0.20 g/kg cellulase(group 6)were added respectively when the ratio of rice straw to Chinese cabbage waste was 5:5.0.030 g/kg Lactobacillus plantarum+0.30 g/kg cellulase(group 7),0.035 g/kg Lactobacillus plantarum+0.20 g/kg cellulase(group 8),0.040 g/kg Lactobacillus plantarum+0.25 g/kg cellulase(group 9)were added respectively when the ratio of rice straw to Chinese cabbage waste was 6:4,and the control group(group CK).The nutrients and quality of silage were measured at 15,30 and 45 days respectively.The results showed that the average sensory scores of silage group(group 1,2,3)with 4:6 ratio of rice straw to Chinese cabbage waste were higher than those of other groups,and the sensory scores of silage group at 45 days were also higher than other groups.The average content of crude protein(Crude protein,CP)and water soluble carbohydrate(Water soluble carbohydrate,WSC)and relative feed value(Relative feed value,RFV)in silage group(group 1,2,3)with 4:6 ratio of rice straw to Chinese cabbage waste were higher than that in other groups,while the average content of neutral washing fiber(Neutral washing fiber,NDF)and acid washing fiber(Acid washing fiber,ADF)were significantly lower than that in other groups(P<0.01).The pH of each silage group was the lowest at 45 days of silage.The pH of group 1,2,3 were below 4.0 at 45 days of silage,and the pH of group 1,2,3 were lower than other groups at each silage period.The ratio of ammonia nitrogen to total nitrogen(Ammonia nitrogen/total nitrogen,NH3-N/TN)were lower in the silage group(group 1,2,3)with the ratio of rice straw to Chinese cabbage waste was 4:6.Except group CK,the content of lactic acid(Lactic acid,LA)and total score of fermentation quality of other silage groups were also the highest at 45 days of silage,and the average value of LA and total score of fermentation quality of group 1,2 and 3 were also higher than that of other groups.Correlation analysis and fit analysis showed that the content of CP and RFV were positive correlation quadratic curve relation with the content of LA and total score of fermentation quality respectively,but negative correlation quadratic curve relation with pH.To sum up,this part of the experiment showed that the silage group(group 1,2,3)with 4:6 ratio of rice straw to Chinese cabbage waste increased the content of CP and LA,RFV,total score of fermentation quality,reduced pH,NH3-N/TN,and silage nutrition and quality were better than other groups at 45 days of silage.Experiment 2:Effect of different treatments on the microflora of mixed silage of rice straw and chinese cabbage wasteOn the basis of experiment 1,the bacterial and fungal flora of silage group(groupl,2,3)and control group(group CK)were determined by the ratio of rice straw to Chinese cabbage waste was 4:6 for 45 days of silage.The correlation between the relative abundance of bacteria and fungi in silage,the correlation between silage nutrient and the relative abundance of bacteria and fungi,and the correlation between silage quality and the relative abundance of bacteria and fungi were analyzed.The results showed that there was no significant difference in the relative abundance of Firmicutes,Ascomycota and Basidiomycota(P>0.05).The relative abundances of Lactobacillus in group 1,2 and 3 were significantly higher than those in group CK(P<0.01),and the relative abundances of Proteobacteria,Leuconostoc were significantly lower than those in group CK(P<0.01),and the relative abundances of Enterobacter and Fusarium were significantly lower than those in group CK(P<0.05).Correlation analysis shows that the relative abundance of Lactobacillus and Basidiomycota were positively correlated with the content of CP,LA,RFV and total score of fermentation quality,but negatively correlated with the content of dry matter(DM),NDF,ADF,acetic acid(AA),NH3-N/TN and pH.The relative abundance of Proteobacteria and Enterobacter and Ascomycota and Fusarium and Penicillium were positively correlated with DM,NDF,ADF,AA,NH3-N/TN,pH,but negatively correlated with CP,LA,RFV and total score of fermentation quality.The relative abundance of Fusarium and Penicillium were negatively correlated with that of Lactobacillus.To sum up,this part of the experiment showed that,compared with the control group(group CK),the silage group(group 1,2,3)with the ratio of rice straw to Chinese cabbage waste was 4:6 were not only improved the nutrition and quality of mixed silage,but also increased the relative abundance of beneficial bacteria such as Lactobacillus in mixed silage,thus reduced the pH and the relative abundance of harmful bacteria such as Fusarium of mixed silageExperiment 3:Effect of mixed silage of rice straw and chinese cabbage waste on rumen fermentation in vitroIn this experiment,the control group(group CK)and the silage group(group1.2,3)with the ratio of rice straw to chinese cabbage waste was 4:6 for 45 days of silage were tested in vitro.The feeding value of each group was evaluated by rumen fermentation parameters,in vitro gas production parameters,fiber degradation and structure observation The results showed that when cultured in vitro for 12 hours,the concentration of microbial protein(Microbial protein,MCP)in group 2 was significantly higher than that in group CK(P<0.05),the concentration of total volatile fatty acids(Total volatile fatty acids,TVFA)in group 1,2,3 were significantly higher than that in group CK(P<0.01)and the highest in group 2.When cultured in vitro for 24 hours,there was no significant difference in the concentration of MCP among all groups(P>0.05),but group CK was the lowest,TVFA concentration in group 3 was significantly higher than group CK(P<0.01).When cultured in vitro for 36 hours,the concentration of MCP in group l and 2 were significantly higher than that in the group CK(P<0.05)and the highest was group 2.The concentration of TVFA in group 1 and 2 were significantly higher than that in the group CK(P<0.05)and the highest was group 2.There was no significant difference in the cumulative gas production between groups(P>0.05).The theoretical maximum gas production and potential gas production of group 1 and 2 were significantly higher than those of group CK(P<0.01),and the highest gas production was found in group 2.Although there was no significant difference in 36 h degradation rate of NDF and ADF between groups(P>0.05),the highest degradation rate of NDF 36 h was group 2,and the highest degradation rate of ADF 36 h was group 3.In addition,in vitro fermentation was observed by electron microscopy compared with group CK,straw fiber structure of group 1,2 and 3 were degraded to different degrees,and a large number of microorganisms were attached to the surface of group 2 and 3,and the degradation degree were all higher than that of group 1 and CK;however,compared with group 3,straw of group 2 had similar surface structure and severe degradation of subepidermal cells,and there are many cracks in the beam structure due to degradation Therefore,the degradation degree of group 2 was the highest.The correlation analysis showed that there was a positive correlation between the content of CP and cumulative gas production and the concentration of MCP.To sum up,this part of the experiment showed that compared with other groups,the rumen fermentation parameters of the group 2 was better,and the degree of fiber degradation was also higher,so the feeding value of the group 2 was relatively high.In conclusion,the higher nutrition and quality of mixed silage with ratio of rice straw to chinese cabbage waste was 4:6(group1,2,3),and the relative abundance of Lactobacillus was higher than that of group CK,and the relative abundance of Fusarium and Penicillium were lower than that of group CK.The content of CP and LA,RFV and total score of fermentation quality were positively correlated with relative abundance of Lactobacillus,but negatively correlated with relative abundance of Fusarium and Penicillium.The relative abundance of Fusarium and Penicillium were negatively correlated with that of Lactobacillus.When the ratio of rice straw to Chinese cabbage waste was 4:6,0.035 g/kg Lactobacillus plantarum,0.25 g/kg cellulase(group 2),mixed silage for 45 days,its feeding value was relatively high,and the higher content of nutrient increased the relative abundance of Lactobacillus,decreased the pH and Fusarium,and promoted the quality of silage. |
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