Effects Of Compound Bacteria And Fermentation Time On Nutritional Value And In Vitro Fermentation Characteristics Of Whole-plant Millet Silage

This experiment was conducted to study the effects of silage additives and silage time on the nutritional components and Cornell Net Carbohydrate and Protein System(CNCPS)components of whole-plant millet silage.The whole-plant millet silage in the filling stage was used as raw material for silage.There were four groups in the experiment.The control group(CK group)did not add any silage additives,the bacterial enzyme compound preparation group(XL group,containing Lactobacillus plantarum,Lactobacillus brucei,Pediococcus pentosaceus and cellulase)was added at a dose of 5 g/t,the bacterial preparation group 1(BL group,containing Lactobacillus brucei,Lactobacillus plantarum,and Pediococcus pentosaceus)was added at a dose of 10 g/t,and the bacterial preparation group 2(HY group,containing Bacillus subtilis,Lactobacillus acidophilus,and Candida utilis)was added at a dose of 10 g/t.The samples were collected on the 45,60,75,and 90th day of silage,and the sensory evaluation,nutritional components,fermentation quality,CNCPS components,microbial diversity,and rumen degradation rate of the whole-plant millet silage were analyzed.The results showed that:1)The sensory evaluation results of the CK,XL,and BL groups were all excellent in the first grade,and the HY group was good in the second grade(P<0.05).At 45 days of silage,the dry matter content was the highest(P<0.05),and the crude fat content was the lowest(P<0.05).The crude protein content was the highest at 60 days of silage(P<0.05).Compared with the CK group,the dry matter content of the XL group increased significantly(P<0.05),and the crude protein content of the HY group increased significantly(P<0.05).2)Compared with the CK group,the pH value of the XL and BL groups decreased significantly(P<0.05).The content of ammonia nitrogen in the BL group was significantly lower than that in the other three groups(P<0.05),and the content of organic acid was significantly higher than that in the other three groups(P<0.05).The content of ammonia nitrogen at 45 d was significantly lower than that at the other three time points(P<0.05),and the content of lactic acid at 60 d was the highest(P<0.05).3)Silage additives changed the CNCPS components of whole-plant millet silage.Compared with the CK group,the non-protein nitrogen content of the XL and BL groups decreased significantly(P<0.05),and the medium-speed degradation protein content increased significantly.The BL group reduced the proportion of PA in protein and increased the proportion of PB in protein.4)Silage additives changed the bacterial phylum level community structure of whole plant grass silage at 45 d and 90 d.The dominant bacteria in the four groups were and Proteobacteria,and the abundance of Firmicutes in the BL group was significantly higher than that in the other three groups at 45 d(P<0.05).The dominant flora of the four groups at the genus level at 45 d and 90 d of silage were Lactobacillus and Pediococcus,and the abundance of Lactobacillus in the BL group was significantly higher than that in the other three groups at 45 d of silage(P<0.05).5)In vitro fermentation experiments showed that the dry matter digestibility(DMD)of the BL group was significantly higher than that of the other three groups at 45 d and 90 d(P<0.05).At 60 d and 75 d,the DMD of the BL and XL groups was significantly higher than that of the HY and CK groups(P<0.05).The DMD of silage at 60 d,75 d,and 90 d was significantly higher than that at 45 d(P<0.05),but there was no significant difference between the three-time points(P>0.05).The 48 h ammonia nitrogen concentration of the XL Group and BL group was significantly lower than that of the HY group and CK group at each time point(P<0.05).48 h TVFA and 48 h gas production in XL and BL groups were significantly higher than those in HY and CK groups at each time point(P<0.05).The ammonia nitrogen concentration at 48 h of silage at 60 d,75 d,and 90 d was significantly lower than that at 45 d(P<0.05).The total volatile acid content at 48 h and gas production at 48 h were significantly higher than those at 45 d(P<0.05),but there was no significant difference between the three-time points(P>0.05).In summary,each silage additive improved the silage quality of the whole-plant millet silage to a certain extent.The silage additive(BL)containing Lactobacillus buchneri,Lactobacillus plantarum,and Pediococcus pentosaceus had the best effect,and the minimum start-up time of whole-plant millet silage was 60 days.