不同复合添加剂对饲料桑与王草混合青贮品质与微生物多样性的影响

Effects of Different Compound Additives on Quality and Microbial Diversity of Mixed Silage of Forage Mulberry and King Grass

【目的】研究不同复合添加剂对饲料桑(Morus alba L.)与热研4号王草(Pennisetum purpureum×Pennisetum americanum cv.Reyan No.4)混合青贮品质和微生物多样性的影响。【方法】采用随机区组试验设计,设置对照组(CK)、复合菌制剂组(J,植物乳杆菌+枯草芽孢杆菌)、复合酶制剂组(M,纤维素酶+木聚糖酶)和复合菌酶制剂组(JM,植物乳杆菌+枯草芽孢杆菌+纤维素酶+木聚糖酶)4个处理组,每组6个重复,青贮60 d后,分析青贮饲料的营养成分、发酵品质和微生物多样性,并使用V-score评分体系、模糊数学隶属函数法对发酵效果进行评价。【结果】与CK组相比,其余各组混合青贮饲料的青贮品质均有不同程度提升,其中J、M、JM组粗蛋白质、可溶性碳水化合物含量显著升高(P<0.05),中性洗涤纤维、酸性洗涤木质素、氨态氮含量、pH显著降低(P<0.05);M组的酸性洗涤纤维含量显著降低(P<0.05),JM组的乳酸、乙酸含量显著升高(P<0.05)。各组均未检测到丙酸、丁酸。各组V-score评分均在85分以上,其中JM组评分最高(88.93分)。各组隶属函数均值大小排序为JM>J>M>CK。与CK组相比,其余各组青贮微生物Shannon指数、Simpson指数、Chao1指数、Ace指数均显著下降(P<0.05)。在门水平上,各组混合青贮饲料中微生物优势菌门为厚壁菌门(Firmicutes)、变形菌门(Proteobacteria),与CK组相比,J、JM组的厚壁菌门相对丰度显著提高、变形菌门相对丰度显著降低(P<0.05);在属水平上,与CK组相比,J、M、JM组的植物乳杆菌属(Lactiplantibacillus)相对丰度显著提高,肠杆菌科未分类属(unclassified_Enterobacteriaceae)相对丰度显著降低(P<0.05),J、JM组芽孢杆菌属(Bacillus)相对丰度显著提高(P<0.05),JM组肠杆菌属(Enterobacter)相对丰度显著降低(P<0.05)。【结论】添加复合菌制剂、复合菌酶制剂或复合菌酶制剂均能不同程度改善饲料桑与王草混合青贮营养成分、发酵品质,且能提高有益菌丰度、降低有害菌丰度。综合考虑,添加复合菌酶制剂更适合饲料桑与王草混合青贮。

【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.