Effect Of Additives On Silage Quality,microbial Community Structure And Metabolites Of Caragana Korshinskii

Caragana korshinskii is a woody plant of the legume family with high feeding value,which is rich in protein,minerals,various amino acids and some functional substances.However,the cellulose and lignin contents will relatively increase as the fertility of caragana korshinskii advances,and the poor palatability and utilization rate seriously limit its exploitation.Silage can better preserve the nutrient content and improve palatability of forage,however,Caragana korshinskii silage alone is difficult to obtain high quality silage forage.In this experiment,Caragana korshinskii in full-bloom stage was used as the research material,treatments were designed as without additives(control group,CK),the corn flour addition group(C),the fiber complex enzyme addition group(F)and the corn flour+fiber complex enzyme addition group(CF).These silos were kept at room temperature,and silage fermentation quality,microbial community structure and metabolites,were analyzed after 60 days of fermentation.The results will provide a scientific basis for the production of high quality Caragana korshinskii silage.The main results of this study are as follows:(1)Effects of corn meal and Fiber Complex enzyme on silage quality of Caragana korshinskiiThe results showed that the C,F and CF groups all improved the fermentation quality and nutritional quality of caragana korshinskii silage,and group C had the best nutritional quality of silage and group CF had the best fermentation quality of silage.The AN_N,PA,ADF,ADL content and yeast count in the C,F and CF groups were highly significant lower than those in the control group(P<0.01),The DM content and number of lactic acid bacteria was highly significant higher than the control group(P<0.01),The NDF content was significant higher than the control group(P<0.05);pH and NDF were lower in C,F and CF groups than in the control group,where pH content was highly significant lower in F and CF groups than in the control group(P<0.01);The LA,CP and WSC contents in groups C,F and CF were higher than those in control group,with the LA content in group CF being extremely significantly higher than that in control group(P<0.01),and the contents of CP and WSC in group C were significantly higher than those in control group(P<0.01).(2)Effects of corn meal and fiber complex enzyme on microbial community structure of Caragana korshinskii silageThe results showed that the aroma intensity index,chaol and ace index of caragana korshinskii silage in C,F and CF groups were higher than the control group.The dominant genera in the silages of the different treatment groups were Bifidobacterium and Bacteroides;the dominant species are Bacteroides fragilis and Bacteroides vulgatus.The abundance of Lactobacillus and Lactobacillus parafarraginis was reduced in the C,F and CF groups,while the abundance of Weissella and Weissella_paramesenteroides was increased in the CF group.Correlation analysis showed a significant negative correlation(P<0.05)between pH and Sphingomonas;LA had a highly significant positive correlation with Faecalibacterium(P<0.01);NDF had a significant negative correlation with Bifidobacterium and Bifidobacterium_breve(P<0.05);ADF had a significant negative correlation with Faecalibacterium and Bacteroides_vulgatus(P<0.05);ADL had a significant negative correlation with Bacteroides_vulgatus(P<0.05).(3)Effects of corn meal and Fiber complex enzyme on metabolites of Caragana korshinskii silageMetabonomics results showed that a total of 228 substances were detected in caragana korshinskii silage of different treatments,of which 52 were differential metabolites,most of which were organic acids,carbohydrates and alcohols.The main pathways enriched for different treatment silage differential metabolites were carbon metabolism,ABC transporter and sulfur metabolism.Functional metabolites and marker metabolites related to silage fermentation were different in different treatment groups,and caragana korshinskii silage fermentation was regulated in different ways,these signature functional metabolites have metabolism-promoting,disease-preventing,antibacterial and antimicrobial,and antioxidant effects.In conclusion,both corn flour and fiber complex enzyme additives can improve the fermentation quality of Caragana korshinskii silage,and single-molecule real-time sequencing technology and untargeted metabolomics allow us to understand the complex microbial communities and biochemical reaction processes of forage silage more precisely,which provides technical and theoretical support for regulating high-quality Caragana korshinskii silage.