Effects of silage additives on fermentation and mechanism for improved fermentation quality

以未枯萎青贮料、鸭茅青贮料和紫花苜蓿青贮料为试验材料，研究了添加甲酸、接种剂和复合菌剂对青贮料中乳酸菌发酵品质、有氧腐烂和干物质体外消化率的影响。无论青贮期长短，添加甲酸处理的青贮料发酵品质均好于未处理青贮料。甲酸处理对提高紫花苜蓿青贮料的发酵品质效果显著。经接种剂处理的一次和二次切段Timothy青贮料的发酵品质较好，二次切青贮的发酵品质改善幅度小于一次切青贮料。通过添加接种剂和加酶处理，提高了蒂莫西青贮料、二次青贮料和第一次青贮料的发酵品质。由此可见，添加剂对青贮料品质的影响取决于所用牧草原料的种类、收割频率和收割日期。这些结果证实，虽然甲酸或接种剂或接种剂和酶能改善Timothy青贮料和鸭茅青贮料的发酵品质，但甲酸并不能阻止这些青贮料的好氧脱绿。然而，接种剂或接种剂和酵素均能延长青贮料的有氧稳定性。甲酸处理青贮料中乳酸菌的优势种是植物乳杆菌，无论采用何种草料，该种乳酸菌的发生率都在77.4%以上。接种剂处理的青贮料主要含有干酪乳杆菌鼠李糖亚种。该菌株与添加接种剂为同一菌种，在体外干物质消化率有提高的趋势，添加添加剂改善了青贮料的品质。

The effects of adding formic acid, bacterial inoculant or a mixture of bacterial inoculant and enzymes on the fermentation quality flora of lactic acid bacteria, aerobic deterioration and in vitro digestibility of dry matter of grass silages were investigated using unwilted or wilted timothy, orchardgrass and alfalfaThe fermentation quality of formic acid-treated silages of timothy, orchardgrass and alfalfa silages were better than that of the untreated each silage, irrespective of cutting date. The formic acid teatment was markedly effective for the improvement of the fermentation quality of alfalfa silages. The fermentation quality of the inoculant-treated first and second cut timothy silages were good, while the fermentation quality of the second cut orchardgrass silage was improved less than that of the first cut silage. The fermentation quality of the first and second cut timothy silages and first cut orchardgrass silage was increased with treatments of inoculant and enzymes. From the above results, the effectiveness of additives on the silage quality depends on the species of herbage materials used, the cutting frequency and the cutting date.These results confirm that though formic acid or inoculant or inoculant and enzymes improve the fermentation quality of timothy and orchardgrass silages, formic acid is not to prevent the aerobic dererioration of these silages. However, inoculant or inoculant and enzymes are able to prolong the aerobic stability of silages.The dominant species of lactic acid bacteria in formic acid-treated silages were Lactobacillus plantarum irrespective of the species of grass materials used and the incidence of this species was over 77.4%. The inoculant-treated silages included mainly Lactobacillus casei subsp.rhamnosus. This strain was same species as adding inoculant.In vitro digestibility of dry matter tend to increase in the silages of good quality improved by use of additives.