Effects Of Dandelion Flavonoids On Antioxidant Activity,Fermentation Quality And Microbial Community Structure Of Caragana Korshinskii Silage

Silage is an important part of ruminant diet,therefore,producing green and safe silage is an important measure to ensure the health of livestock and promote the sustainable development of animal husbandry.Caragana korshinskii is a legume shrub widely used for windbreak and sand fixation.It is rich in nutrients such as protein,amino acids,various minerals,vitamins and other nutrients,so it can be used as an important supplement for roughage resources of ruminants.Taraxacum mongolicum is a perennial herb of compositae.Taraxacum mongolicum flavonoids have antioxidant,antibacterial and anti-inflammatory functions,but its application in silage is relatively less.Therefore,in this experiment,Caragana korshinskii was used as silage material,and dandelion active ingredient flavonoids(FT)were used as additives,the addition amounts were set to 0%(CK),0.5%(FT1),1.0%(FT2),1.5%(FT3)and 2.0%(FT4)/FM,respectively.The effects of dandelion flavonoids on the antioxidant activity,fermentation quality and microbial community structure of Caragana korshinskii silage were studied.Providing theoretical basis and practical reference for solving the shortage of feed resources,developing Caragana korshinskii as a local feed resource and exploring green and healthy antibiotic alternatives as silage additives.The main results of this study are as follows:(1)Compared with CK group,different amounts of dandelion flavonoids could improve the antioxidant activity of Caragana korshinskii silage.During the whole silage process,T-AOC decreased first and then stabilized.The activity of GSH-Px increased first and then stabilized.SOD activity did not change much during the whole silage process.After 60 days of silage,different amounts of dandelion flavonoids significantly increased the T-AOC,GSH-Px activity and DPPH free radical scavenging ability of Caragana korshinskii silage(P<0.01).The T-AOC of FT4 group was the highest(2.90 mmol/g),and the SOD activity of FT4 group was significantly higher than that of CK group(P<0.01).The antioxidant activity of Caragana korshinskii silage was the best when the addition of dandelion flavonoids was 2.0%.(2)Compared with CK group,the DM content of Caragana korshinskii silage was significantly increased in different amounts of dandelion flavonoids(P<0.01),and the DM content of FT3 group was significantly higher than that of the other three dandelion flavonoids groups(P<0.01),and the content was 43.35%.The CP content in FT3 and FT4 groups were significantly increased(P<0.01),and the contents of NDF and ADF were significantly decreased(P<0.01).Compared with CK group,the pH value and AN_TN content of FT3 and FT4 groups were significantly decreased(P<0.05),the contents of LA and AA were significantly increased,the AA content of FT4 group was significantly higher than that of the other three dandelion flavonoid groups(P<0.01),which was 1.23%.PA and BA were not detected in each group.Excepting the FT1 group,the number of lactic acid bacteria in other groups were significantly higher than that of CK group(P<0.01),and no yeast and mold were detected in each group.Principal component analysis showed that the antioxidant activity and fermentation quality of Caragana Korshinskii silage improved best when the dandelion flavonoids supplemental level was 2.0%.(3)Different amounts of dandelion flavonoids reduced the microbial Alpha diversity of Caragana korshinskii silage.Excepting the FT3 group,the number of OTUs in each group was lower than that in CK group.The results of microbial community analysis showed that the dominant bacteria in each group gradually changed from Proteobacteria to Firmicutes with the addition of dandelion flavonoids.At the genus level,with the addition of dandelion flavonoids,the relative abundance of Pseudomonas decreased significantly,and the relative abundance of Lactobacillus increased significantly.At the species level,the dominant bacteria in CK and FT1 groups were Pardosa_pseudoannulata,and the dominant bacteria in the other groups were Lactobacillus_plantarum,Lactobacillus_parafarraginis,etc.There were differential microorganisms in all groups excepted FT1 group,and the differential microorganisms in dandelion flavonoids treatment group were more conducive to silage fermentation.Different amounts of dandelion flavonoids were beneficial to promote the growth of beneficial bacteria and inhibit the growth of bad bacteria,which improved the antioxidant activity and silage fermentation quality of Caragana korshinskii silage.For example,Lactobacillus was significantly positively correlated with AA of Caragana korshinskii silage,Lactobacillus_parafarraginis was significantly positively correlated with LA content of Caragana korshinskii silage,but significantly negatively correlated with ADF content.In summary,different amounts of dandelion flavonoids could improve the antioxidant activity of Caragana korshinskii silage,improve the nutritional quality and fermentation quality of Caragana korshinskii silage,optimize the microbial community structure,promote the growth of beneficial bacteria,and inhibit the growth of bad bacteria.When the amounts of dandelion flavonoid was 2.0%,it had obvious effect.