不同含水量和菌剂对紫花苜蓿裹包青贮质量的影响

Effects of Moisture Contents and Inoculants on Quality of Wrapped Alfalfa Silage

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(Aspergillus 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p H、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p H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p H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% and45% were supplemented with Aspergillus oryzae,Lactobacillus plantarum and no inoculants respectively to evaluate 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 p H 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 p H 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 from70% to 45%,supplementing A. oryzae lowered p H 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 acetobacter 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 important 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.