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

以未萎蔫和萎蔫的梯牧草、鸭茅和苜蓿为试材，研究了添加甲酸、菌剂及菌剂与酶混合物对青贮饲料乳酸菌植物群发酵品质、好氧劣变和干物质体外消化率的影响。鸭茅和苜蓿青贮效果优于未处理的各青贮，与刈割期无关。甲酸处理对改善苜蓿青贮饲料发酵品质效果显著。接种处理的一茬和二茬梯牧草青贮发酵品质较好，而二茬鸭茅青贮发酵品质的提高幅度小于一茬。接种剂和酶制剂处理提高了一茬、二茬梯牧草和一茬鸭茅青贮的发酵品质。结果表明，添加剂对青贮饲料品质的影响取决于所用牧草的种类、刈割次数和刈割期，说明甲酸、接种剂、接种剂和酶制剂都能改善梯牧草和鸭茅青贮饲料的发酵品质，但甲酸不能防止青贮饲料的有氧劣化。但接种剂或接种剂加酶制剂能延长青贮饲料的有氧稳定性，无论使用何种草料，甲酸处理青贮饲料中的乳酸菌均以植物乳杆菌（Lactobacillus plantarum）为优势菌，其检出率均在77.4%以上。接种剂处理的青贮饲料主要包括干酪乳杆菌鼠李糖亚种。该菌株与添加接种剂的品种相同，添加剂对品质好的青贮饲料干物质体外消化率有提高的趋势。

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.