Enzymes have been successfully used to improve the nutritional value of cereal based feeds for pigs and poultry since the early eighties. Their benefits derive from improved digestion of nutrients following the destruction of anti-nutritional compounds such as β-glucans and arabinoxylans and the augmentation of the animal's existing enzyme arsenal where this may be sub-optimal. In the ruminant sphere fibrolytic enzymes have been used as aids to silage preservation for almost as long. Their action here is to enhance natural sugar levels by the breakdown of structural carbohydrates - an action which can concurrently render the fibre more amenable to digestion by rumen microbes.