The non-starch polysaccharides (NSPs) of cereals exhibit anti-nutritive activity when present in broiler diets. The high levels of arabinoxylans (pentosans) in rye and β-glucans in barley are responsible for the poor nutritive value of these cereals. Australian wheats vary considerably in their nutritive value with some having very low apparent metabolizable energy (AME <13 MJ/kg) values. Recent studies have shown that the low AME wheat problem is probably due to the variation in the levels of the water-soluble wheat NSPs which are predominantly pentosans. When pentosans isolated from rye or wheat are added to broiler diets, dose-dependent depressions in nutrient digestion and growth occur. Several treatments have been shown to be effective in improving the nutritive value of cereals. Soaking the cereals in water or adding NSP-degrading enzymes decreases the anti-nutritive activity of the NSP. Addition of antibiotics to diets also has been shown to increase the nutritive value of diets with high levels of NSP suggesting that the action of these materials is, at least in part, mediated by the gut microflora.

A total of 360 I-d-old broiler chickens were fed on a diet based on rye and wheat in equal proportions without or with supplementation of increasing levels (0.11, 0.22, 0.44 and 0.88 g/kg) of a technical enzyme preparation containing pentosanase and β-glucanase activities. In vitro investigations revealed that the enzyme preparation solubilized pentosans, increasing the relative viscosity of buffer extracts from enzyme-supplemented diets. Enzyme supplementation generally improved body-weight by approximately 27% at day 15 and 15% at day 27, increased feed intake by 15 and 8% respectively, and improved feed conversion efficiency by 10 and 5% respectively. There was also a decreased occurrence of sticky droppings. Enzyme supplementation increased the digestibility of organic matter, crude protein (nitrogen x 6.25) and starch measured in the last third of the small intestine, and of organic matter and crude fat measured in excreta. Solubilization of insoluble pentosans by the enzyme included led to negative digestibility values for soluble pentosans in the small intestine at the higher levels of supplementation. Most of the dietary fibre degradation observed occurred before the middle section of the small intestine, with some degradation of soluble fibre in the caeca and colon. The solubilization and disruption of feed endosperm cell walls by enzyme supplementation probably was primarily responsible for the observed improvements in digestibility and production results.