Nutrient Contents and In vitro Ruminal Fermentation of Tropical Grasses Harvested in Wet Season in the Philippines

摘要

In tropical countries, perennial grasses are the key feed resources for ruminants; grasses having high nutritional characteristics are important for maintaining the productivity and health of animals. In this study, the nutrient composition and in vitro ruminal degradation characteristics as well as the short-chain fatty acid (SCFA) production of 7 grasses grown over short cutting intervals were compared with those of corn and rice straw. Grasses were harvested at 35 – 39 days after regrowth in the wet season in Laguna, Philippines. Crude protein (CP) contents were not remarkably different among the grasses (from 9 to 11% in a dry matter (DM) basis, p>0.05). Neutral detergent fiber (NDF) contents varied from 63% to 73% DM (p<0.05); the lowest was found in Napier grass ( Pennisetum purpureum ) and the highest in Para grass ( Brachiaria mutica ). Non-fiber carbohydrate (NFC) content was the highest in corn, followed by Jarra grass ( Digitaria milanjiana ) and Gamba grass ( Andropogon gayanus ) (p<0.05). The in vitro NDF degradability was also the highest in corn, followed by that in Jarra grass and Guinea grass ( Panicum maximum ) (p<0.05). SCFA production and gas production was the highest in corn, followed by Jarra grass, Guinea grass, and Signal grass ( Brachiaria decumbens ), and the lowest in rice straw (p<0.05). These findings suggested that the nutritional characteristics, particularly NFC and NDF contents, and rumen degradation varied across grasses harvested at short cutting intervals. Among the grasses investigated in this study, Jarra grass and Guinea grass contained potentially high nutritive value due to the highest rumen fermentation characteristics