A Repeatable Model System for Silage Fermentation in Culture Tubes

Abstract

To develop a model system for silage fermentation that is simple, rapid, and repeatable by using storable plant materials, we made several experiments of simulated silage fermentation in culture tubes. In these experiments, we used milled alfalfa hay cubes (AHC) mixed with certain amounts of water and glucose (AHC medium) and a lactic acid bacterium (LAB) was cultivated together with or without a butyric acid bacterium (BAB) and a coliform bacterium (CFB) under anaerobic conditions. The pure culture of LAB in AHC medium produced lactic acid within 24h of incubation. The mixed culture of CFB with LAB and BAB promoted butyric fermentation. Butyric acid was produced only with high temperature (more than 30°C), low dry matter content of AHC medium (less than 20%), and prevention of lowering the medium pH. Low soluble sugar content of the medium (0. 35%) or smaller inoculum size of LAB (less than 10⁶ cfu/g)than that of CFB (10⁷cfu/g) was effective for the prevention of lowering the medium pH. This modelsystem seemed to be useful for screening of LAB as a silage inoculant.