NONSTARCH POLYSACCHARIDES AND BROILER PERFORMANCE ON DIETS CONTAININGSOYBEAN-MEAL AS THE SOLE PROTEIN-CONCENTRATE

The total water-soluble and water-insoluble non-starch polysaccharides (NSP) were determined in seven soyabean meals processed in Australia, three soyabean meals processed in the U.S.A., and one sunflower meal processed in Australia. Sunflower meal had a higher content of total N SP than any of the soyabean meals, due mainly to increased concentrati ons of cellulose and xylose in the insoluble NSP and uronic acids in t he soluble NSP. Galactose and fucose concentrations were much greater in the insoluble NSP of soyabean meals. Soyabean meals processed in th e U.S.A. had lower concentrations of total NSP, cellulose and xylose t han equivalent meals processed in Australia. Broiler chickens fed diet s containing soyabean meal as the sole dietary protein concentrate gre w significantly more poorly than broilers fed isoenergetic and isonitr ogenous diets in which approximately 25% of the soyabean meal was repl aced with sunflower meal. There was a significant (P < 0.05) negative correlation (r2 = 0.57) between the water-soluble xylose content of th e soyabean meals and the improvement in growth observed with sunflower meal supplementation. Multi-enzyme preparations designed to act on so yabean meal NSP substrates failed to induce any improvement in the gro wth of broilers fed soyabean meal diets. The poor performance of broil ers fed the soyabean meal diets did not appear to be related to inadeq uate processing or to the NSP content or composition of the soyabean m eals. Measurement of free sugars in the supernatant of the digesta in the ileum indicated that the stachyose derived from the oligosaccharid es of soyabean meals appeared to exert an antinutritive effect when so yabean meal was present at high concentrations as the sole protein con centrate in broiler diets.