Plant cell wall polysaccharides are degraded by microorganisms provided that they produce the necessary enzymes and in sufficient quantities. Some polysaccharides, such as hemicelluloses, are highly complex branched structures, which require a wide range of enzymes for their degradation. A further complication in the hydrolysis of these polysaccharides occurs because some sugar residues are esterified to phenolic compounds, such as p -coumaric and ferulic acids. Feruloyl groups reduce accessibility of enzymes to the main chain and may also act as nucleation sites for lignification. Feruloyl esterases and arabinofuranosidases which work in synergy with main enzymes to increase the removal of phenolics, including lignin, should enable xylanolysis and cellulolysis to proceed more effectively. The effect of enzyme preparations rich in debranching enzymes on the degradation of poor quality roughage was examined.