Methane production of two roughage and total mixed ration as influenced by cellulase and xylanase enzyme addition

摘要

In recent decades supplementation of animal feeds with exogenous fibrolytic enzymeshas substantially improved digestibility and animal performance. However, informationrelated to associated methane production is limited and inconsistent. This study evaluated theeffect of cellulase and xylanase enzymes on in vitro methane production of Eragrostis curvulahay, maize (Zea mays) stover and a total mixed ration (TMR) at seven levels of the two enzymes.Feed samples were incubated for 2, 12, 24 and 48 h in an in vitro batch culture with buffer andrumen fluid, and fibrolytic enzymes. Gas production was measured using a pressure transducerconnected to a data tracker, while methane gas was analysed using a gas chromatograph whichwas calibrated with standard CH4 and CO2. Increases in the level of enzyme application resultedin increases in gas volume, total volatile fatty acid (VFA) production, dry matter (DM) disappearanceand associated increases in methane production. The linear increase in percentage andvolume of methane production in tandem with increases in level of enzyme application mightbe due to increased fermentation, and organic matter degradability that resulted in a shift inVFA production towards acetate. Considering the efficiency of DM and neutral detergent fiberdegradation and production of associated VFA with levels of enzymes, the use of 1 mg g−1 DMof enzyme can be a good option for the feeds tested. However, they cannot decrease methaneproduction. It will be very important to consider other hydrogen sinks that can capture directlyextra H+ produced by the addition of enzyme so that their supplementation could be very efficientand environmentally sound.