乳酸菌对苜蓿草粉发酵品质的影响

Effects of lactic acid bacteria on fermentation quality of alfalfa meal

通过为期60d的发酵,探讨添加乳酸菌对苜蓿(Medicago sativa)草粉发酵品质的影响。试验设4个处理,分别为添加无菌水(对照)、植物乳杆菌(Lactobacillus plantarum,LP)、屎肠球菌(Enterococcus faecium,EF)和植物乳杆菌+屎肠球菌(LP+EF)发酵苜蓿草粉,设5个时间点采样进行相关项目测定。结果表明,与对照组相比,发酵60d时各试验组发酵苜蓿草粉的评分提高,总酸含量显著升高(P<0.05),pH显著降低;LP、LP+EF和对照组的干物质含量明显低于EF组;各试验组酸性洗涤纤维含量明显低于对照组;有氧暴露7d后,各试验组的pH均显著低于对照组、总酸含量均显著高于对照组(P<0.05),且只有对照组中检测到酵母菌(Saccharomycetes)和霉菌(Mycete)。综上可知,添加乳酸菌对苜蓿草粉的发酵品质、稳定性及营养组成具有良好的改善作用。

This study aimed to investigate the effects of lactic acid bacteria on the fermentation quality of alfalfa meal. There were four treatment groups, including a control group treated with sterile water and experimental groups treated with plant-derived Lactobacillus pLantarurn only, excrement-derived Enterococcus faeciurn only, or both of them together. Alfalfa meal samples were obtained and analysed at several time points. Each group had three replicate samples at each time point. The results showed that, compared with the control group, each treatment group had a good sensory assessment score, and all treatment groups showed an increase in total acid content （P〈0.05） and a decrease in the pH of the alfalfa silage after 60 d. The dry matter content was higher in the group treated only with E. faecium than in the other groups. There were no significant differences in acid detergent fibre content among the three experimental groups （P〈0.05）, but all the experimental groups had a lower acid detergent fibre content than the control group. After exposing the samples to air for 7 d, wefound that the pH were significantly lower in the experimental groups than in the control group, whereas the opposite pattern was observed for total acid content. Yeast and mould were only observed in the control group. In conclusion, fermentation of alfalfa meal with L. plantarum or E. faecium had positive effects on its quality, stability, and chemical composition.