Abstract: 【Objective】 This experiment was conducted to study the effects of different combinations of additives on the quality and microbial diversity of mixed silage of forage mulberry (Morus alba L.) and king grass (Pennisetum purpureum×Pennisetum americanum cv.Reyan No.4).【Method】 A randomized block design was used to set up four treatment groups:control group (CK),compound bacteria preparation group (J,Lactobacillus plantarum＋Bacillus subtilis),compound enzyme preparation group (M,cellulase＋xylanase) and compound bacteria enzyme preparation group (JM,Lactobacillus plantarum＋Bacillus subtilis＋cellulase＋xylanase),with 6 replicates in each group.After 60 days of silage,the nutrient content,fermentation quality and microbial diversity of silage were analyzed,and the fermentation effect was evaluated by V-score scoring system and fuzzy mathematics membership function method.【Result】 Compared with CK group,the silage quality of the other groups of mixed silage was improved to varying degrees,the contents of crude protein and soluble carbohydrate in J,M and JM groups were significantly increased (P＜0.05),and the contents of neutral detergent fiber,lignin,ammonia nitrogen and pH were significantly decreased (P＜0.05),the content of acid detergent fiber in group M was significantly decreased (P＜0.05),and the content of lactic acid and acetic acid in group JM was significantly increased (P＜0.05).The propionic acid and butyric acid was not detected in each group.The V-score of each group was above 85 points,and the JM group had the highest score of 88.93 points.The order of the mean value of membership function in each group was JM＞J＞M＞CK.Compared with the CK group,the Shannon index,Simpson index,Chao1 index and Ace index of silage microorganisms in other groups decreased significantly (P＜0.05).At the phylum level,the dominant microbial phylum in each group of mixed silage was Firmicutes and Proteobacteria.Compared with CK group,the relative abundance of Firmicutes in J and JM groups was significantly increased,and the relative abundance of Proteobacteria was significantly decreased (P＜0.05).At the genus level,compared with CK group,the relative abundance of Lactiplantibacillus in J,M and JM groups was significantly increased,and the relative abundance of unclassified_Enterobacteriaceae was significantly decreased (P＜0.05).Additionally,compared with CK group,the relative abundance of Bacillus in J and JM groups was significantly increased (P＜0.05),and the relative abundance of Enterobacter in JM group was significantly decreased (P＜0.05).【Conclusion】 In conclusion,the addition of compound bacteria preparation,compound bacteria enzyme preparation or compound bacteria enzyme preparation could improve the nutrient content and fermentation quality of mixed silage of forage mulberry and king grass to varying degrees,and could increase the abundance of beneficial bacteria and reduce the abundance of harmful bacteria.Comprehensive consideration,adding compound bacteria enzyme preparation was more suitable for mixed silage of forage mulberry and king grass.

Key words: forage mulberry; king grass; mixed silage; nutrient content; fermentation quality; microbial diversity