The Study Of Oat Straw Mixed Ensilage With Tall Fescue Or Perennial Ryegrass In Tibet

Laboratory-scale experiments were conducted to determine the effects of comzyme and molasses to preserve mixed silage of oat straw in Tibetan pasturing area. The six parts involved in this paper were:the study of the fermentation quality of mixed silages of oat straw with tall fescue or perennial ryegrass; the effect of comzyme on the fermentation quality of mixed silages of oat straw with tall fescue; the effect of molasses on the fermentation quality of mixed silages of oat straw with tall fescue; the effect of comzyme on the fermentation quality of mixed silages of oat straw with perennial ryegrass and the effect of molasses on the fermentation quality of mixed silages of oat straw with perennial ryegrass. The silos were opened on 7,14,30, and 60 days of ensiling, separately. Three silos are used for each treatment and ensiling days.In Exp.1 and Exp.2, the experiment was design of four groups. The results showed:compared with the control group, treatment groups significantly reduced pH value, ammonia nitrogen/total nitrogen value and total VFAs content,and significantly increased lactic acid content. However, the final pH value of the mixed silage was still expected more than 4.5, lactic acid content less than 40g kg-1DM and ammonia nitrogen/total nitrogen value remaining high, which indicated that the fermentation quality of the mixed silage was improved, but not yet to reach the standard of favorable silage.In Exp.3,40% oat straw with 60% tall fescue mixedly ensiled as the control group,three treatment groups adding comzyme on the basis of the control group at the level of1.5ml/kg (E-1),2.0ml/kg (E-2) and 2.5ml/kg (E-3),respectively (fresh weight basis). The results showed:three treatment groups all reduced the final pH value to a favorable rang (4.3 below) and significantly(P<0.05)lower than the control group, while three treatment groups haved higher lactic acid content and lower acetic acid content. However, all treatment groups haved low dry matter and WSC content as well as the control group, and ammonia nitrogen/total nitrogen value of the treatment groups was higher or significantly (P<0.05) higher than of the control group. It suggested that the addition of comzyme accelerated fermentation, however, because of high nutrition lossed, the mixed silage fermentation quality was not significantly improved.In Exp.4, the control group was the same with the Exp.3, three treatments adding molasses on the basis of the control group at the level of 3%,4% and 5%, respectively (fresh weight basis; denoted M-1, M-2, M-3, respectively. The results showed:compared with the control group, M-1 significantly reduced pH value, ammonia nitrogen/total nitrogen value and total VFAs content, and significantly (P<0.05) raised LA/AA value and lactic acid content. It indicated that M-1 enhanced lactic acid bacteria fermentation and improved the mixed silage quality. Through M-2 also improved the mixed silage quality, 30 days later, the mixed silage was not well preserved. M-3 improved the mixed silage to a certian extent, but not evidently. By Integrated assessment:the addition 3% molasses were the optimal level and 30 day was the optimal ensiling time.In Exp.5,60% oat straw with 40% perennial ryegrass mixedly ensiled as the control, three treatment groups adding comzyme on the basis of the control group at the level of 1.5ml/kg (E-1),2.0ml/kg (E-2) and 2.5ml/kg (E-3), respectively (fresh weight basis). The results showed:the addition of comzyme all reduced the mixed silage pH value, significantly (P<0.05) increased lactic acid content and LA/AA value and significantly (P<0.05) decreased total VFAs content.However, the addition of comzyme on ammonia nitrogen/total nitrogen value and WSC content was to no effect, and dry matter losses of three treatment groups were higher than of the control group. By Integrated assessment: the addition of comzyme accelerated lactic acid bacteria fermentation. however, because of high nutrition lossed, the mixed silage fermentation quality was not significantly improved.In Exp.6, the control group was the same with the Exp.5, three treatment groups adding molasses on the basis of the control group at the level of 3%,4% and 5%, respectively (fresh weight basis; denoted M-1, M-2, M-3, respectively). The results showed:the mixed silage of the control group and three treatment groups all haved low pH value (4.27 below) and high lactic acid content (92.91 g kg-1DM above) to achieve a favorable rang. However, in the ensling prophase, the rate of pH decrease and lactic acid increase of the control group silage is slow, which did not effectively inhibit the activities of harmful microorganisms and protease activity, so ammonia nitrogen/total nitrogen value of the control group was significantly (P<0.05) higher than three treatment groups. It suggested that addition of molasses could quickly reduce the pH value and rapidly increase lactic acid content, which reduced the ammonia nitrogen/total nitrogen value and increased WSC content. By Integrated assessment:the addition of molasses promoted fermentation of lactic acid bacteria and speed up the fermentation process, thereby further improving the mixed silage quality. In each level, the addition of 4% molasses was the best.