添加纤维素酶和淀粉对象草青贮发酵品质的影响

Effects of Adding Cellulase and Starch on Fermentation Quality of Napier Grass Silage

本试验旨在探究添加纤维素酶和淀粉对象草青贮发酵品质的影响,为提高象草青贮品质提供理论基础。试验以象草为青贮原料,设对照组、添加纤维素酶组(试验Ⅰ组)、混合添加纤维素酶与淀粉组(试验Ⅱ组),发酵30 d后测定象草青贮的营养成分含量、发酵品质、微生物数量和微生物多样性。结果表明:1)试验Ⅰ组、试验Ⅱ组的水溶性碳水化合物含量均高于对照组,且试验Ⅱ组与对照组的差异达到极显著水平(P<0.01);试验Ⅰ组、试验Ⅱ组的中性洗涤纤维、酸性洗涤纤维含量均低于对照组,且试验Ⅱ组与对照组的差异达到显著水平(P<0.05)。2)试验Ⅰ组、试验Ⅱ组的pH均极显著低于对照组(P<0.01),试验Ⅰ组、试验Ⅱ组之间差异不显著(P>0.05);乳酸、乙酸含量以及乳酸/乙酸值由高到低的顺序为试验Ⅱ组>试验Ⅰ组>对照组,但组间差异不显著(P>0.05);试验Ⅰ组、试验Ⅱ组的弗氏评分显著高于对照组(P<0.05)。3)乳酸菌数量由高到低顺序为试验Ⅱ组>试验Ⅰ组>对照组,但组间差异不显著(P>0.05),所有样品均未检出酵母菌和霉菌。4)试验Ⅱ组特有操作分类单元(OTU)数、Chao1指数和ACE指数均高于对照组和试验Ⅰ组;试验Ⅰ组、试验Ⅱ组的Shannon指数、Simpson指数均高于对照组;厚壁菌门是3组象草青贮的绝对优势菌门,且由高到低的顺序为试验Ⅱ组>试验Ⅰ组>对照组;试验Ⅰ组和试验Ⅱ组的魏斯氏菌属相对丰度高于对照组。综上所述,单独添加纤维素酶和混合添加纤维素酶与淀粉均能够提高象草青贮的营养成分含量、发酵品质、乳酸菌数量、微生物多样性、厚壁菌门和魏斯氏菌属的相对丰度,且混合添加纤维素酶与淀粉对象草青贮发酵品质的提高效果较佳。

The purpose of this experiment was to explore the effects of adding cellulase and starch on fermentation quality of napier grass silage,thus provide a theoretical basis for improving the quality of napier grass silage.Napier grass was used as silage material,and divided into control group,adding cellulase group(trial groupⅠ),adding the mixture of cellulase and starch group(trial groupⅡ),and the nutrient contents,fermentation quality,microbial population and microbial diversity of napier grass silage after 30 day’s fermentation were determined.The results showed that the water soluble carbohydrate content of trial groupⅠand trial groupⅡwere higher than the control group,and the difference between trial groupⅡand control group reached extremely significant level(P<0.01);the contents of neutral detergent fiber and acid detergent fiber of trial groupⅠand trial groupⅡwere lower than those of control group,and difference between trial groupⅡand control group reached significant level(P<0.05).2)The pH of trial groupⅠand trial groupⅡwas extremely significantly lower than that of control group(P<0.01),but there was no significant difference between the trial groupⅠand trial groupⅡ(P>0.05);the contents of lactic acid,acetic acid and the lactic/acetic ratio from high to low was trial groupⅡ>trial groupⅠ>control group,but there was no significant difference among groups(P>0.05).The Flieg’s score of trial groupⅠand trial groupⅡwas significantly higher than that of control group(P<0.05).3)The population of lactic acid bacteria from high to low was trial groupⅡ>trial groupⅠ>control group,but there was no significant difference among groups(P>0.05).And no yeast and mold were detected in all samples.4)Operational Taxonomic Unit(OTU)number,Chao1 index and ACE index of trial groupⅡwere higher than those of control group and trial groupⅠ;the Shannon index and Simpson index of trial groupⅠand trial groupⅡwere higher than those of control group.Firmicutes was the absolute dominant phylum in three groups of napier grass silage,and the order from high to low was trial groupⅡ>trial groupⅠ>control group.The Weissella relative abundance of trial groupⅠand trial groupⅡwas higher than that of control group.In summary,single adding cellulase and combined adding cellulase and starch can improve the nutrient contents,fermentation quality,lactic acid bacteria population,microbial diversity,and the relative abundance of Firmicutes and Weissella.The improvement effects of fermentation quality of napier grass silage by combined adding cellulase and starch are better.