Abstract

The objective of this study was to evaluate the effects of lactic acid bacteria (LAB) inoculants on fermentation quality and subsequent in vitro gas production, ruminal fermentation parameters, cellulolytic bacteria and their activities of alfalfa silage. Primary growth of alfalfa (Medicago sativa L.) was harvested at 50% flowering stage, inoculated without (control) or with Lactobacillus plantarum, Enterococcus mundtii and Enterococcus faecalis at 1.0 × 10⁶ cfu/g of fresh weight (FW) in quadruplicate laboratory silos for 45 d. The silage inoculated with LAB were well preserved, indicated by the lower (p < .05) pH and ammonia-N content and the higher (p < .05) dry matter (DM), organic matter (OM), crude protein and lactic acid contents than the control silage. In vitro asymptotic gas and total volatile fatty acids production were higher in all LAB-treated silages (p < .05). All inoculants increased carboxymethyl-cellulase and β-glycosidase activities, and obtained higher DM and neutral detergent fibre degradability (p < .05) except E. mundtii. Similarly, L. plantarum and E. faecalis inoculants had higher (p < .05) Ruminococcus albus and Fibrobacter succinogenes relative proportions than the control. However, L. plantarum inoculants had lower (p < .05) percentage of methane (CH₄) in 72 h gas production than the control and E. faecalis inoculants. These results suggested that L. plantarum were more effective in enhancing alfalfa silage utilisation by promoting forage digestibility and reducing ruminal CH₄ emission than E. mundtii and E. faecalis.

• HIGHLIGHTS

• Lactic acid bacteria (LAB) inoculants improved alfalfa silage quality.

• Silage treated with Lactobacillus plantarum or Enterococcus mundtii increased gas production but reduced the percentage of methane in vitro.

• L. plantarum and Enterococcus faecalis promoted neutral detergent fibre digestibility by increased rumen cellulolytic bacteria proportion and cellulase activity.

摘要

这项研究的目的是评估乳酸菌（LAB）接种剂对发酵质量和随后的体外产气量，瘤胃发酵参数，纤维素分解细菌及其苜蓿青贮饲料活性的影响。在一式三份的实验室中，苜蓿（苜蓿）的初生期在开花期达到50％时收获，接种时不接种（对照）或用植物乳杆菌，芒氏肠球菌和粪肠球菌以1.0×10 ⁶ cfu / g鲜重（FW）接种筒仓45 d。用LAB接种的青贮饲料得到了很好的保存，这表明较低的 pH （p <.05）和氨氮含量较高，而较高的（p  <.05）干物质（DM），有机物（OM），粗蛋白和乳酸含量均高于对照青贮饲料。在所有LAB处理的青贮饲料中，体外渐进气体和总挥发性脂肪酸的产生均较高（p  <.05）。所有接种增加羧甲基纤维素酶和β糖苷酶的活动，并获得较高的DM和中性洗涤纤维降解性（p 除<.05）E. mundtii。类似地，植物乳杆菌和粪肠球菌接种物具有更高的（p  <0.05）瘤胃球菌球菌和Fibrobacter succinogenes的比对照的相对比例。然而，植物乳杆菌接种物在72小时产气中 的甲烷（CH ₄）百分比（p <.05）低于对照和粪肠球菌接种物。这些结果表明，与普通肠杆菌和粪肠球菌相比，植物乳杆菌通过促进饲料的消化率和降低瘤胃CH _4的排放来提高苜蓿青贮饲料利用率更有效。

• 强调

• 乳酸菌（LAB）孕育剂改善了苜蓿青贮饲料的质量。

• 用植物乳杆菌或普通肠球菌处理的青贮饲料可增加产气量，但减少了体外甲烷的含量。

• 植物乳杆菌和粪肠球菌通过增加瘤胃纤维素分解细菌的比例和纤维素酶的活性来促进中性洗涤剂纤维的消化率。