不同添加剂对构树青贮饲料发酵品质及微生物多样性的影响

Effects of Different Additives on Fermentation Quality and Microbial Diversity of Paper Mulberry Silage

本试验旨在探究不同添加剂对构树青贮饲料发酵品质及微生物多样性的影响。将晾晒3.5 h的构树枝叶添加4%糖蜜作为对照(CK组),在添加糖蜜的基础上分别添加乳酸菌(L组)、纤维素酶(C组)、乳酸菌+纤维素酶(LC组)后进行青贮。青贮60 d后开封测定其营养成分、发酵品质、有氧稳定性及微生物群落结构。结果显示:1)与CK组相比,各添加剂组干物质和粗蛋白质含量显著增加(P<0.05),酸性洗涤纤维和中性洗涤纤维含量显著降低(P<0.05)。2)与CK组相比,各添加剂组pH显著降低(P<0.05),乳酸含量显著升高(P<0.05);各组均未检测到丁酸;所有组氨态氮/全氮均低于10%,LC组氨态氮/全氮最低(7.69%),且其水溶性碳水化合物含量显著高于其余各组(P<0.05)。3)各组有氧稳定性均较好,有氧稳定时间表现为LC组>C组>L组>CK组。4)在门水平上,各组的优势菌均是厚壁菌门,其次是变形菌门;在属水平上,CK组的优势菌为魏斯氏菌属,C组、L组、LC组的优势菌是肠球菌属,相对丰度分别为42.00%、60.54%和68.32%,呈增长趋势。综上可知,在添加糖蜜的基础上单独或混合添加乳酸菌与纤维素酶均能改善构树青贮饲料的发酵品质,同时引起微生物群落结构发生变化,减少有害微生物的数量。

This study aimed to explore the effects of different additives on the fermentation quality and microbial diversity of paper mulberry silage.Addition of 4%molasses was added to the paper mulberry which drying for 3.5 h in the air as the control(CK group).On the basis of adding molasses,lactic acid bacteria,cellulase and lactic acid bacteria+cellulase were added for ensiling,which were recorded as L group,C group and LC group,respectively.Nutrients,fermentation quality,aerobic stability and microbial community structure of silage were determined after 60 days of ensiling.The results showed as follows:1)compared with the CK group,the contents of dry matter and crude protein were significantly increased and the contents of acid detergent fiber and neutral detergent fiber were significantly decreased in all additive groups(P<0.05).2)The pH was significantly lower and the lactic acid content was significantly higher in all additive groups than those in the CK group(P<0.05).Butyric acid was not detected in each group,and the ammonia nitrogen/total nitrogen in all groups was lower than 10%.The ammonia nitrogen/total nitrogen in LC group was the lowest(7.69%),while the content of soluble carbohydrate in LC group was significantly higher than that in the other groups(P<0.05).3)The aerobic stability in each group was good,and the aerobic stabilization time was ranked as LC group>C group>L group>CK group.4)At the phylum level,the dominant bacteria in each group were Firmicutes,followed by Proteobacteria.At the genera level,the dominant bacteria in CK group was Weissella,while the dominant bacteria in C group,L group and LC group was Enterococcus with the relative abundance of 42.00%,60.54%and 68.32%,respectively,which showed an increase trend.In conclusion,on the basis of adding molasses,adding lactic acid bacteria and cellulase in paper mulberry silage alone or in combination can significantly improve the fermentation quality and change the microbial community to reduce the number of harmful bacteria.