Aerobic Deterioration of Napiergrass (Pennisetum purpureum Schum.) Ensiled with Molasses after Opening the Silo

Abstract

Aerobic deterioration after opening the silo was studied for direct-cut and wilted napiergrass (Pennisetum purpureum Schum.) ensiled with molasses from sugarcane. The grass was ensiled in a polyethylene bag silo, that was 35cm in diameter and 30cm in height. Moisture contents of the direct-cut and the wilted grass were 86.5% and 78.2%, respectively. Thermistor was placed in the centre of the silage to determine changes of temperature in the silage after exposure to air. After 5months, silages were exposed to air by removing the top of the bag silo. After exposure, temperature in silages increased, reached a highest peak and then decreased. Maximum temperature and time to the highest peak were 34.0°C on day 10, and 39.5°C on day 9 after exposure to air for the direct-cut and the wilted silage, respectively. Silage samples from top layer (5cm below the top surface), middle layer (15cm below the top) and bottom layer (25cm below the top) were taken on 0, 2, 6, 10 and 14 days after exposure to air. The mean pH and lactic acid content (g/100g DM) of the silages of 3 1ayers at day 0 were 3.79 and 10.61, and 4.07 and 6.95 for the direct-cut and the wilted silage, respectively. After exposure to air, pH gradually increased and lactic acid content decreased with time. Top layer silage was enough to keep the pH low against aerobic deterioration for 5 and 2 days in the direct-cut and the wilted silages, respectively.