Tropical fodder trees are commonly used as supplement to grass feeding. Usually supplemental foliage is used without any additional energy source. Therefore, the potential of fodder trees to increase microbial biomass production (due to foliage N capture for microbial growth) might not be achieved. In addition, it has been suggested that forage digestibility might be stimulated if an energy source, ideally, locally available, is provided with the foliage. Thus, the objective of the present experiment was to assess the DMD of Leucaena leucocephala and Manihot esculenta (cassava) mixtures, and the in vitro gas production of Leucaena-cassava-grass mixtures.