The chemical composition of grass silages prepared with and without pre-treatment with inoculants containing Lactobacillus plantarum

Abstract

Two experiments are described in which silage inoculants containing Lactobacillus plantarum as the active principle were applied to perennial ryegrass ( Lolium perenne), which was ensiled in 2-kg capacity silos. In the first experiment, wilted ryegrass (304 g dry matter (DM) kg −1) was ensiled without additive treatment, or with the addition of 2 × 10 4, 1 × 10 5, 1 × 10 6, or 1 × 10 7 Lactobacillus plantarum/kg ensiled grass. Increasing quantities of bacteria applied to herbage resulted in decreases in the quantities of ammonia-nitrogen (expressed as a proportion of total nitrogen), and increases in the quantities of residual water-soluble carbohydrate and lactic acid in the silages. In the second experiment, ryegrass was ensiled either without a field-wilting period (187 g DM kg −1), or after 20 h (194 g DM kg −1) or 48 h field wilting (240 g DM kg −1). At each DM level, the grass was ensiled without additive treatment, or with the addition of 6.8 × 10 4, 9.1 × 10 4 or 3.4 × 10 7 L. plantarum/kg ensiled grass. The treatment which contained 6.8 × 10 4 bacteria, also contained cellulase, hemicellulase and amylase enzymes. Irrespective of the DM at which the grass was ensiled, when compared with the untreated silages, the application of inoculants reduced silage pH and concentrations of ammonia-N (expressed as a proportion of total N), acetic and butyric acids, and increased the concentrations of residual water-soluble carbohydrate and of formic and lactic acids in silage DM. These effects were most apparent when 3.4 × 10 7 bacteria were applied/kg grass; inclusion of enzymes in the inoculant did not have any measurable effect upon silage composition.