本研究旨在探讨青贮发酵对玉米秸秆感官指标、发酵品质、营养成分以及门、纲、目、科和属5个水平细菌群落构成及丰度的影响。将去穗后仍青绿的蜡熟期玉米秸秆切短揉搓至1~2 cm,将水分调节至65%~70%后,取青贮前样品(3个重复)和青贮后样品(3个重复)使用聚乙烯袋真空包装,室温贮藏45 d后开启取样,运用实验室检测手段及MiSeq高通量测序技术分析青贮前后玉米秸秆品质及菌群结构的变化。结果表明:1)青贮发酵45 d后的玉米秸秆青贮饲料呈黄绿色,质地较好,呈酸香味。青贮发酵作用能够使玉米秸秆pH迅速降低(P<0.05),乳酸含量显著增加(P<0.05),中性洗涤纤维(NDF)及酸性洗涤纤维(ADF)含量有下降趋势(P>0.05)。2)玉米秸秆经过青贮发酵后,变形菌门(Proteobacteria)、γ-变形菌纲(Gammaproteobacteria)、肠杆菌目(Enterobacteriales)、肠杆菌科(Enterobacteriaceae)和魏斯氏菌属(Weissella)菌群数量显著降低(P<0.05);青贮发酵能够显著增加厚壁菌门(Firmicutes)、芽孢杆菌纲(Bacilli)、乳杆菌目(Lactobacillales)、乳杆菌科(Lactobacillaceae)、片球菌属(Pediococcus)和乳杆菌属(Lactobacillus)菌群数量(P<0.05)。综上,青贮发酵改善玉米秸秆感官指标、发酵品质以及营养成分的同时,可以有效降低有害细菌的数量,增加有益菌的数量,从而可以降低致病菌对家畜健康存在的潜在风险。通过实验室检测手段及Miseq高通量测序技术相结合,能够在分析青贮品质的同时,提供青贮前后整个菌落构成及丰度变化的信息,进而为发酵过程的调控提供依据。
The objective of the present study was to investigate the effects of ensiling process of corn stalk silage on its sensory indicators, fermentation quality, nutrition composition and bacteria composition and abundance in phylum, class, order, family and genus. Green and dough stage corn stalk without ear was chopped to 1 to 2 cm with water content of 65% to 70%. Each three samples were collected and packaged by vacuum packager in polyethylene bags before and after ensiling process. After being stored at room temperature for 45 days, changes of the silage quality and bacteria composition were analyzed using laboratory testing methods and MiSeq sequencing technology. The results showed as follows: 1) the corn silage was yellow-green and had the good texture and smell after ensiling 45 days. The pH was rapidly increased (P<0.05), the lactic acid content was significantly increased (P<0.05), while the content of neutral detergent fiber (NDF) and acid detergent fiber (ADF) had the downward trend (P>0.05). 2) After ensiling of corn silage, the numbers of Proteobacteria plylum, Gammaproteobacteria class, Enterobacteriales order, Enterobacteriaceae family and Weissella genus were significantly decreased (P<0.05), while the numbers of Firmicutes phylum, Bacilli class, Lactobacillales order, Lactobacillaceae family, and Pediococcus and Lactobacillus genus were significantly increased (P<0.05). In conclusion, ensiling process can improve the sensory indicators, fermentation quality, nutrition composition with effectively reducing the amount of harmful bacteria and increasing the number of beneficial bacteria, which can reduce the potential risk to animal health pathogens exist. Combing laboratory testing methods and MiSeq sequencing technology can provide the information of silage quality and the composition and abundance of bacteria, which can provide the basis for the regulation of the fermentation process.
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