Fermentation quality of mixed silage of Alfalfa and Italian Ryegrass at different ratio was studied. The two species of pasture were cut into 1 -2cm lengths, divided equally into Group A, B, C and D according to the ratio of the fresh weight of green fodder of 2：8, 3：7, 4：6 and 5：5, and ensiled after being fully mixed. The resuits： pH and dry matter content of each group showed decreasing trend with the ensiling time passing. On the 30th day, pH of Group A and B was about 4. l, and significantly lower than about 4.30 of Group C and D （ P 〈 0.05 ） ; dry matter content of Group B was significantly higher than that of Group C and D （ P 〈 0. 05 ）, but therewas no significant difference between Group B and A （ P 〉 0.05 ） ; AN/TN content of each group continuously increased without exception with the duration of the fermentation treatment. AN/TN content of Group B was slightly higher than that of the other groups in the first three days, and afterwards without exception lower than that of the other groups, and on the 30th day significant difference in AN/TN content showed between Group B and Group D whose AN/TN content was the highest （ P 〈 0.05 ）, but there was no significant difference betweenGruop B and Group A and C （ P 〉 0.05）. Water soluble carbohydrate （WSC） content of the silage showed de- creasing trend during the stage of ensillng, during the first 14 days of which WSC content of Group A was the highest, and on the 30th day of which WSC content of Group B was the highest; but there was no significant difference between each gruop （P 〉 0.05）. On the 30th day, lactic acid content in Group A and B was signifi-canfly higher than that of Group C and D （P 〈 0.05） ; compared with Group C and D, acetic acid content and total volatile fatty acids content of Group B were lower. The ratio of lactic acid / acetic acid was higher, and the differences were all significant（P 〈0.05）. The results showed that good quality silage can be made by mixing I- talian Ryegrass and Alfalfa, and the mixed silage at the ratio of the fresh weight of green fodder of 3： 7 is more suitable.%为研究不同比例紫花苜蓿与意大利黑麦草混合青贮的发酵品质，试验将两种牧草切割至1-2cm，按照鲜草质量比2：8、3：7、4：6和5：5等分为A、B、C、D四个处理组，充分混合后进行青贮。试验结果：各组青贮料的pH值和干物质含量均随青贮时间呈降低趋势，在青贮30d时，A、B组pH值约为4．1，显著低于C、D组的4．30左右（P〈0．05）；干物质含量B组显著高于C、D组（P〈0．05），但与A组之间差异不显著（P〉0．05）；AN／TN的含量随着发酵天数的增加均持续升高，B组的AN／TN含量在青贮前3d稍高于其它三组，而3d后均低于其他三组，且在30d时与含量最高的D组差异显著（P〈0．05），但与A、C组差异均不显著（P〉0．05）。青贮料中可溶性糖含量在青贮过程中均呈逐渐降低的趋势，其中在青贮前14d均以A组的WSC含量最高，青贮30d时，B组WSC含量最高，但各组之间差异均不显著（P〉0．05）。在青贮30d时，乳酸含量A、B组显著高于C、D组（P〈0．05）；与C、D组相比，B组乙酸和总挥发性脂肪酸含量低而乳画蔓／乙酸比值高，且差异均显著（P〈0．05）。结果表明：采用意大利黑麦草与紫花苜蓿混合青贮可以获得品质优良的青贮饲料。且以鲜草质量比3：7的混合青贮较为适宜。
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