Nutritive activity of soluble rice brain arabinoxylans in broiler diets.

1. A soluble material (703 g/kg non-starch polysaccharide, 141 g/kg starch and 166 g/kg protein) of low viscosity (termed RB-NSP), was isolated in large quantities from defatted Australian rice bran using a mild alkaline extraction and ethanol precipitation. 2. The soluble non-starch polysaccharide fraction of RB-NSP comprised arabinose (0.40 mol%), xylose (0.32 mol%) galactose (0.17 mol%), glucose (0.08 mol%) and mannose (0.03 mol%). 3. RB-NSP was included at graded concentrations (0, 20, 40 and 60 g/kg) in a sorghum/casein basal diet and the diet fed to male broilers in a classical balance trial to determine apparent metabolisable energy (AME). The AME values recorded were 13.26, 13.85, 14.26 and 14.00 MJ/kg DM with a significant correlation (r = 0.65, P < 0.001) between dietary RB-NSP inclusion rate and dietary AME. 4. Feeding RB-NSP had no effect on growth, food conversion ratio or the digestibilities of starch and protein which were both high (0.98-0.99 and 0.88-0.89, respectively). 5. It was concluded that the RB-NSP may have been a substrate for hindgut fermentation in the broiler but that it possessed no anti-nutritive activity.