730-1 The Ensilability of Forage Grasses in a Wet Tropical Environment.

Wednesday, 8 October 2008
George R. Brown Convention Center, Exhibit Hall E
Kyle J. Barber, Tropical Plant and Soil Sciences, University of Hawaii Manoa, Honolulu, HI and Russell Yost, 3190 Maile Way, Room 102, St. John Building, University of Hawaii, Honolulu, HI
In a wet tropical environment forage conservation has many issues. Hay making is difficult and uncertain as high humidity requires long field drying time and frequent and/or unexpected precipitation will damage the herbage resulting in loss of dry matter (DM) and quality. Silage is an alternative conservation method. This research is focused on the ensilability of two tropical grasses, Brachiaria mutica and Pennisetum purpureum “Bana”. B. mutica and P. purpureum were analyzed for forage quality and then ensiled in 56-ml mini silos after being chopped to <1 cm. Grasses were either ensiled directly or wilted prior to ensilage. After 30 d silos were opened and silage was analyzed for DM loss, pH, lactic acid, and butyric acid. Results show that P. purpureum produced good quality silage with the majority of acids produced being lactic acid (88% to 93%) and no detectable butyric acid. Lactic acid values were 4% and 5.4% DM resulting in pH 4.5 and 5.65 of direct cut and wilted forages, respectively. Results of B. mutica showed that it produced less desirable silage. Low lactic acid production of 0.2% and 2.8% DM resulted in a higher pH, 5.3 for direct cut and 6.65 for wilted forage. Dry matter loss of both wilted P. purpureum and B. mutica were low at 1.4% and 3.7% respectively. Dry matter loss of P. purpureum and B. mutica were reduced by approximately 10% and 11%, respectively by wilting the grasses. Initial conclusions are P. purpureum produces acceptable silage while B. mutica does not. It is hypothesized that the water soluble carbohydrates in B. mutica were not insufficient for the required fermentation. Further research to test this hypothesis will be presented.