Effect of Different Rates of Ethanol Additive on Fermentation Quality of Napiergrass (Pennisetum Purpureum) (Report‪)‬

INTRODUCTION It is only under anaerobic conditions that lactic acid bacteria (LAB) can dominate fermentation, and achieving and maintaining the anaerobic conditions during the ensiling of forage was very important (McDonald, 1991). However, this is not always possible in practice because many crops contain too much moisture and most farm silos are of such a size that they cannot be filled in one day. Previous studies indicated that the fermentation of the initial aerobic phase in the silos was crucial for successful silage (Shao et al., 2002, 2005). The amount of atmospheric oxygen trapped in a sealed silo is used up rapidly by the respiratory system of the plants and the quantity of soluble carbohydrate metabolized is negligible. Studies by Greenhill (1964) indicated that plant cell breakdown and the release of plant juices by plasmolysis is a prerequisite for the development of the LAB during the early stage of ensiling. The infiltration of even small amounts of air is thought to delay both plasmolysis and the onset of pH reduction. As a result, the presence of oxygen in the silo encourages the development of yeasts and causes an increase in the number of Gram-negative bacteria. In most cases, delayed sealing or a mass of atmosphere trapped in the silo resulted in a reduction in the amount of lactic acid produced and frequently a normally dominant lactic acid bacterial fermentation was replaced by a clostridial one (McDonald, 1991). In addition to a reduction in the level of fermentable carbohydrates, other effects of trapped oxygen have been noted. The energy released by the oxygen respiration of carbohydrate metabolism is responsible for a rise in temperature of ensiled herbage, which can bring about extensive chemical changes to the protein (Kim et al., 2006).