Fibrolytic Enzymes May Improve in Vitro Degradability of Tropical Forages.

Tropical forages typically may have poor nutritional value due to its high amount of fibre in their chemical composition compromising the sustainability of livestock production and resulting in high enteric methane (CH4) emissions. In order to increase fibre degradability and energy utilization efficiency from low quality forages, exogenous fibrolytic enzymes have been studied. In this assay we evaluated the effects of increasing dose levels of fibrolytic enzymes extract (FEE) produced by Trichoderma reesei, on in vitro organic matter degradability, fermentation parameters, total gas and CH4 production of tropical forages. Forages samples were analyzed for their chemical composition. Enzyme activity from FEE was performed for xylanase and endoglucanase. The in vitro gas production technique was used in a 4 x 3 factorial arrangement with four FEE dose levels (5, 50, 500 and 5000 µL) and three substrates (Cynodon spp., Panicum maximum, and Cenchrus ciliaris L.) plus the control (substrate without FEE addition). The highest dose level increased (p < 0.05) degradability, total gas and CH4 production in all substrates. Butyrate and ammonia nitrogen concentration also increased while acetate-to-propionate ratio and pH decreased (p < 0.05) with the addition of FEE. These results indicated that the use of fibrolytic enzymes produced through agricultural resources can be a reliable way to improve degradability of low quality forages, contributing to the sustainability and intensification of livestock production in tropical countries.