不同含水量和菌剂对紫花苜蓿裹包青贮质量的影响

摘要

选用4个含水量（80％、70％、55％和45％）的紫花苜蓿（Medicago sativa）分别添加米曲菌（Asper-gillus oryzae）、植物乳杆菌（Lactobacillus plantarum）和不添加菌剂进行裹包青贮。在青贮45 d 开包取样，分析各处理青贮苜蓿干基的 pH、氨态氮和总氮变化、微生物菌落和有机酸指标，探讨不同含水量和菌剂及其互作对紫花苜蓿裹包青贮质量的影响。结果表明，80％含水量的裹包青贮苜蓿 pH 和氨态氮数值偏高，乳酸菌极少，乳酸极低，产生了丁酸和丙酸（P ＜0．05，P ＜0．01）；45％含水量的裹包青贮苜蓿酵母菌和霉菌较多，乙酸偏低（P ＜0．01）；70％和55％含水量的裹包青贮苜蓿其所有测试指标较佳（P ＜0．05，P ＜0．01）。随着苜蓿含水量由70％降低至45％，添加米曲菌维持低 pH 值、抑制酵母菌和霉菌菌落和增加乳酸（P ＜0．05，P ＜0．01）；添加植物乳杆菌减少氨态氮和乙酸菌产生，降低乙酸（P ＜0．05）。含水量和菌剂对裹包青贮苜蓿乳酸菌和乙酸菌菌落有互作，导致乳酸和乙酸测值变化（P ＜0．05）。由此结论，含水量比添加菌剂对苜蓿裹包青贮质量的影响更为显著，70％和55％含水量的紫花苜蓿裹包青贮效果较好；添加米曲菌促进乳酸菌发酵产生乳酸；添加植物乳杆菌降低氨态氮产生，减少低含水量的乙酸菌产生乙酸。%The alfalfa (Medicago sativa)with 4 different moisture contents of 80%,70%,55% and 45% were supplemented with Aspergillus oryzae,Lactobacillus plantarum and no inoculants respectively to e-valuate the effects of moisture and inoculants on the quality of wrapped alfalfa silage.After ensiling for 45 days,the silage samples were taken and the pH value,NH3 -N and total N content,microbial colonies and organic acids were analyzed.The results showed that the wrapped alfalfa silage with 80% moisture had higher pH and NH3 -N values,and extremely low lactic acid bacteria and lactic acid.The butyric acid and propionic acid were also observed (P <0.05,P <0.01 ).The wrapped alfalfa silage with 45% moisture had more yeast and mold colonies,and lower acetic acid content (P <0.01 ).That with 70% or 55% moisture achieved the best estimates (P <0.05,P <0.01 ).With the moisture contents of wrapped alfalfa silage decreasing from 70% to 45%,supplementing A.oryzae lowered pH value,inhibited yeast and mold colonies and promoted the production of lactic acid(P <0.05,P <0.01 );while supplementing L.plantarum reduced NH3 -N and ace-tobacter colonies,and lowered acetic acid content (P <0.05).The moisture and inoculants of wrapped alfalfa silages had interaction effects on lactic acid bacteria and acetobacter colonies,which resulted in the changes of lactic acid and acetic acid production (P <0.05).It is concluded that the moisture content was more impor-tant to the wrapped alfalfa silage quality than supplementing inoculants,and that with 70% or 55% moisture contents had the best estimates.Supplementing A.oryzae promoted lactic acid bacteria fermentation to produce more lactic acid,and supplementing L.plantarum lowered NH3 -N value,and reduced acetobacter colonies and acetic acid production with low moisture contents.