THE EFFECT OF INOCULATION WITH LACTOBACILLUS-PLANTARUM ON FERMENTATION IN LABORATORY SILOS OF HERBAGE LOW IN WATER-SOLUBLE CARBOHYDRATE

In experiment 1, a mixture of perennial ryegrass and white clover (176 g DM kg−1) was ensiled with no addition, or with the application of Lactobacillus plantarum, 3 × 106(g fresh weight of herbage)−1 or enterobacteria, 3 × 106 (g fresh weight of herbage)−1 or both of these inoculants. Silos were incubated at either 18°C or 26°C for 7 d and sealing of half of the silos was delayed for 48 h. In experiment 2, cocksfoot (247 g DM kg−1) was ensiled with no additive, with the application of L. plantarum, 4 × 106 (g fresh weight of herbage)−1 enterobacteria, 4 × 106 (g fresh weight of herbage)−1 or ammonium nitrate, 5 g (kg herbage)−1. Silos were incubated at 18°C and sealing was delayed for 48 h. In neither experiment were the untreated silages of satisfactory quality after 35 d ensilage, having pH's of 4·3 and 6·4. and ammonia‐N concentrations of 139 and 209 g N (kg total N)−1 in experiments 1 and 2 respectively. The poorer fermentation in experiment 2 reflected the lower water‐soluble carbohydrate (WSC) content of the ensiled herbage (136 and 53 g WSC (kg DM)−1 in experiments 1 and 2 respectively). Inoculation with L. plantarum significantly reduced silage pH and the concentrations of ammonia‐N (experiment 1 only) and ethanol and increased lactic acid concentrations. Inoculation with enterobacteria had only minor effects in each experiment. In experiment 1, incubation at 26°C increased the rate of fermentation in the silos as pH was significantly lower after 7d incubation at 26°C than at 18°C, but this effect had largely disappeared after 35 d incubation. When sealing of the silos was delayed for 48 h, the resulting silages had significantly higher pH and ammonia‐N contents than silages from silos that had been sealed immediately after filling. In experiment 2, addition of ammonium nitrate significantly reduced the concentrations of ethanol and acetic acid in silages opened after 7 d. After 35 d the concentrations of ethanol were significantly reduced and those of ammonia‐N increased by the addition of ammonium nitrate. There were marked increases in silage pH between 7 and 35 d ensilage and in the concentrations of ammonia‐N and acetic acid in the silages that had been inoculated with ammonium nitrate at ensilage. Copyright © 1990, Wiley Blackwell. All rights reserved