Davies D R, Merry R J, Williams A P, Bakewell E L, Leemans D K, Tweed J K
Institute of Grassland, Aberystwyth, Ceredigion, United Kingdom.
J Dairy Sci. 1998 Feb;81(2):444-53. doi: 10.3168/jds.S0022-0302(98)75596-1.
The effect of contrasting concentrations of water-soluble carbohydrates of herbage on silage fermentation and composition was examined using grass with high [250 g/kg of dry matter (DM)] concentrations of water-soluble carbohydrates and grass and clover with low (66 g/kg of DM) concentrations of water-soluble carbohydrates. Herbages were ensiled untreated, after inoculation with lactic acid bacteria, or after treatment with formic acid. Good quality silages were produced from herbage with high concentrations of water-soluble carbohydrates, regardless of treatment, and all pH values were below 3.7 after 90 d of ensilage. However, the silage formed from inoculated herbage had a significantly lower concentration of ammonia N and a significantly higher proportion of residual ribulose-1,5-bisphosphate carboxylase compared with the other two silages. Fast protein liquid chromatography (Pharmacia, Uppsala, Sweden) was used to measure ribulose-1,5-bisphosphate carboxylase, and measurement of true plant protein fractions in herbage and silage showed benefits over traditional measurements such as the measurement of N and ammonia N. Herbages with low concentrations of water-soluble carbohydrates produced inferior quality silages that had lower ribulose-1,5-bisphosphate carboxylase contents and higher ammonia N contents, regardless of treatment; few significant differences were observed among treatments. Under good ensiling conditions, when available water-soluble carbohydrate is adequate, the use of inoculants can improve fermentation characteristics and increase the ribulose-1,5-bisphosphate carboxylase content of silages. However, when the herbage has low concentrations of water-soluble carbohydrates, even in inoculated herbages, lactic acid bacteria may follow a heterofermentative pathway instead of a homofermentative pathway, which can result in a decrease in silage quality and a reduction in intact ribulose-1,5-bisphosphate carboxylase.
利用水溶性碳水化合物含量高[250克/千克干物质（DM）]的牧草以及水溶性碳水化合物含量低（66克/千克DM）的牧草和三叶草，研究了牧草中不同浓度的水溶性碳水化合物对青贮发酵和组成的影响。牧草未经处理、接种乳酸菌或用甲酸处理后进行青贮。无论采用何种处理方式，水溶性碳水化合物含量高的牧草都能制成优质青贮料，青贮90天后所有pH值均低于3.7。然而，与其他两种青贮料相比，接种牧草制成的青贮料中氨态氮浓度显著降低，残留的1,5-二磷酸核酮糖羧化酶比例显著升高。使用快速蛋白质液相色谱法（瑞典乌普萨拉的Pharmacia公司）测定1,5-二磷酸核酮糖羧化酶，对牧草和青贮料中真实植物蛋白组分的测定显示出优于传统测定方法（如氮和氨态氮的测定）的优势。水溶性碳水化合物含量低的牧草制成的青贮料质量较差，无论采用何种处理方式，其1,5-二磷酸核酮糖羧化酶含量较低，氨态氮含量较高；各处理之间几乎没有显著差异。在良好的青贮条件下，当可利用的水溶性碳水化合物充足时，使用接种剂可以改善发酵特性并提高青贮料中1,5-二磷酸核酮糖羧化酶的含量。然而，当牧草中水溶性碳水化合物含量较低时，即使是接种的牧草，乳酸菌也可能遵循异型发酵途径而非同型发酵途径，这可能导致青贮料质量下降和完整的1,5-二磷酸核酮糖羧化酶减少。
