添加乳酸菌对营养期菊芋茎叶青贮发酵品质动态变化的影响

Effects of additon of lactic acid bacteria on dynamic changes of fermentation quality of jerusalem artichoke stem and leaf silage during vegetative period

摘要:

为研究乳酸菌对菊芋茎叶青贮品质和发酵特性的影响,以菊芋茎叶为试验材料,利用青贮发酵罐调制青贮饲料。以添加0.2%乳酸菌(T)为试验组,不添加乳酸菌(C)为对照组,分别在发酵1、7、15、30、60 d开封,分析添加乳酸菌对菊芋茎叶营养品质、发酵特性及体外产气量和干物质消化率(IVDMD)的影响。结果表明:1)盛花期菊芋茎叶DM含量为320.7 g/kg(鲜样基础),可溶性糖(WSC)含量为22.60%(DM基础),缓冲能值为50.62 mEq/kg(DM基础),较适合制作青贮饲料。2)添加乳酸菌可降低菊芋茎叶青贮饲料pH值、乙酸、丁酸和NH3-N含量(P＜0.05),增加乳酸含量、DM含量、WSC含量,提高感官品质(P＜0.05),而对中性洗涤纤维(NDF)及酸性洗涤纤维(ADF)无显著影响(P＞0.05)。3)随着发酵时间的延长,两处理青贮菊芋的pH值、DM和WSC含量均表现出逐渐下降的趋势,而乙酸、丁酸、NH₃-N和乳酸含量则在第7天显著增加,之后趋缓,第60天最高。4)添加乳酸菌可以增加青贮菊芋体外24 h总产气量和IVDMD(P＜0.05);降低NH3-N含量(P＜0.05);还可以降低体外发酵12和24 h的瘤胃液pH值(P＜0.05)。综上所述,添加乳酸菌可以提高菊芋茎叶青贮饲料的发酵品质和营养价值。

Abstract:

In order to study the effect of lactic acid bacteria on the silage quality and fermentation characteristics of jerusalem artichoke stems and leaves,jerusalem artichoke stems and leaves were used as experimental materials in the experiment,and silage was prepared by silage fermentation tank.0.2% lactic acid bacteria (T) was added in the experimental group,and no lactic acid bacteria (C) was added in the control group.The effects of additon of lactic acid bacteria on the nutritional quality,fermentation characteristics,in vitro gas production and IVDMD of jerusalem artichoke stems and leaves were analyzed after fermentation for 1 d,7 d,15 d,30 d and 60 d.The results showed that :1)The dry matter(DM) content in stems and leaves of jerusalem artichoke at full flowering stage was 320.7 g/kg (fresh sample basis),the water soluble carbohydrate(WSC) content was 22.60/% (DM basis),and the buffer energy value was 50.62 mEqBC/kg (DM basis),which made jerusalem artichoke stems and leaves at this stage more suitable for silage.2)Addition of lactic acid bacteria could reduce pH,acetic acid,butyric acid and NH3-N content of jerusalem artichoke silage (P＜0.05),increase lactic acid content,DM content,WSC content and improve its sensory quality (P＜0.05),but had no significant effect on neutral detergent fibre(NDF) and acid detergent fibre(ADF) (P＞0.05).3)With the extension of fermentation time,the pH,DM and WSC contents of silage jerusalem artichoke in both the experimental and control group showed a gradual downward trend,while the contents of acetic acid,butyric acid,NH3-N and lactic acid increased significantly on the 7th day,then slowed down,and reached the highest value on the 60th day.4)The addition of lactic acid bacteria could increase the total gas production and IVDMD of jerusalem artichoke in vitro for 24 h (P＜0.05) and reduce NH3-N content(P＜0.05).Moreover,rumen fluid pH value of 12 and 24 h in vitro fermentation was decreased.In summary,the addition of lactic acid bacteria can improve the fermentation quality and nutritional value of jerusalem artichoke silage.