Abstract
Three experiments were conducted to examine the fermentation process and the effect of some pre-ensiling treatments on quality and palatability of napiergrass (Pennisetum purpureum SHUMACH). The grasses were harvested four times per year at ten weeks interval and were ensiled in laboratory silos after the following treatments : (1) Sample with no treatment (control), (2) Wilting for 2 to 3 hours (wilting) and (3) Addition of molasses at the rate of 3-9% as silage additive (molasses) in both experiment 1 and 2. In experiment 3, the grasses were harvested four times per year at eight weeks interval and were ensiled in laboratory silos after the following treatments : (1) Sample with no treatment (control), (2) Wilting for 2 to 3 hours (wilting), (3) Inclusion of beat pulp at up to 5% (beet pulp), (4) Inclusion of bagasse at up to 5% (bagasse) and (5) Inclusion of citrus pulp at up to 5% (citrus pulp) as an additive to control water and available carbohydrate content. The fermentative quality of treated silage was either same or higher as compared with the control. The ratio of lactic acid content to total organic acids of the respective silage was increased by these pre-ensiling treatment. The lactic acid content especially was increased to over 10% on average and pH also decreased to under 4.0 in both molasses and citrus pulp treated pulp silages. The fermentative quality of grass harvested and ensiled either autumn or winter season, where the available carbohydrate content was less than 6.0%, was lower than in the other harvest times in all treatments. There were no positive correlation between fermentation quality and palatability by cattle. High palatability was however observed with beet pulp treated silage which have high dry matter digestibility and with wilted treated silage which controlled water content. On the contrary low palatability was observed with molasses and citrus pulp treated silage both of which indicated low pH < 4.0, and with bagasse which had low dry matter digestibility.
