Anti-nutritive activity of wheat pentosans in broiler diets.

1. To assess their possible anti-nutritive activity wheat pentosans were isolated from a milling by-product and added at graded levels to a sorghum-based broiler chicken diet. 2. A water-insoluble pentosan preparation (WIP, 720 g arabinoxylan/kg) caused a depression of apparent metabolisable energy (AME) of 1.63 MJ/kg DM at the highest level of inclusion (41.9 g/kg). Broilers maintained on this diet showed significant growth depression and a decrease in feed conversion efficiency. 3. A water-soluble pentosan preparation (WSP, 520 g arabinoxylan/kg) showed less anti-nutritive activity. 4. In a second experiment the AME of rice (pearled), maize, sorghum, wheat, triticale, barley and rye was determined. The AME values obtained were highly correlated (r = -0.98, P less than 0.001) with the summed levels of pentosans and beta-glucans found in the cereals. 5. It was concluded that the pentosans of wheat possess anti-nutritive activity when present in broiler diets and that similar polysaccharides may influence the nutritive value of other cereals.