Effects of Dry Matter Contents of Silages and Maximum Environmental Temperature During Ensilage on the Occurrence of Aerobic Deterioration

Abstract

Four separate experiments were conducted with wilted Italian ryegrass in order to study the effects of dry matter (DM) contents and maximum environmental temperature durng ensilage on aerobic deterioration. In each experiment, a half of the wilted material was ensiled in PVC bag silos directly (D) and the other half was ensiled after mixing with 20% water (W). A half of the silos was kept in an ordinary room where maximum temperatures above 30°C were recorded for 16 days in the summer, white the remainder was kept in a room of 22°C during the summer. After ensilage of 120-160 days, silages were transferred into expanded polystyrene containers and kept in a room of 25°C for 7 days under aerobic conditions. Changes in temperature were monitored and chemical and microbiological analyses were carried out at the days 0 and 7 of the aerobic exposure. In Experiments 1 and 2, where DM of 'D' silages were 57.4% and 51.80%, respectively, marked yeast growth was observed and temperature rise started earlier showing a peak of temperature at the early stage of aerobic exposure, while temperature rise in 'W' silages started at later stages than 'D' silages. In Experiments 3 and 4, where DM contents of 'D' silages were 47.0% and 33.9%, respectively, yeast counts at day 7 were smaller and onset of temparature rise was rather slower in 'D' than in 'W' silages. There was a trend that higher maximum environmental temperature during ensilage delayed the temperature rise after opening silos.