Abstract:
179 Non-Starch Polysaccharides in Australian Cereals J. S Kopinski, P. Martin, G. W. Blight, A. Pytko and P. Van Melzen Queensland Department of Primary Industries, Animal Research Institute, Yeerongpilly Qld 4 105 Non starch polysaccharides (NSP) are a group of complex carbohydrates which comprise a large component of the cell wall of most cereals. The major components are pentosans and the (l-3), (l-4) B-glucans. The anti-nutritive effects of these nonstarch poly-saccharides are manifested by the depression of nutrient digestion and absorption (Antoniou and Marquardt, 198 1). When poultry are fed a mainly barley-based diet the l3-glucan present causes growth depression accompanied by sticky droppings which can be ameliorated by D-glucanase addition (Gohl et al. 1978). Similarly when poultry are fed ryebased diets (Antioniou and Marquardt, 198 1) or even wheat-based diets (Choct and Annison, 1990) the pentosans present exhibit anti-nutritive activities with lower AME's and growth depression. Little data is available on the levels of these non-starch polysaccharides in the three major cereals used in animal feeding in Australia. The present study examined the levels of B-glucans and pentosans in barley, wheat and sorghum crops grown in 1992. A total of 66 wheat samples (11 varieties x 6 sites), 40 barley samples (10 varieties x 4 sites) and 12 sorghum varieties at one site only, were analysed. It is generally accepted that problems for poultry with the feeding of wheat can be a result of pentosan levels, while barley&glucans also cause problems when used for animal feeding. The results in table 1 indicate that barley has a substantial pentosan content, equivalent to wheat. Thus when barley-based diets are fed to animals an underlying `pentosan' problem may exist which is being masked by the R-glucan effect. Use of R-glucanases in barley diets will increase the importance of the pentosan content of barley on animal performance. Sorghum, although having an insignificant D-glucan content, has a pentosan level 50% of that present in wheat and barley. Site and variety comparisons indicate that wheat pentosans are influenced significantly by site (PcO.05) whereas in barley, variety and not site influences the pentosan content (PcO.05). R-glucan levels in wheat and barley are influenced by both variety and site (PcO.05). It is important for nutritionists to be aware of the level of pentosan in barley, particularly as pentosans along with B-glucans can influence the energy digestibility of diets for non-ruminants, especially poultry, with deleterious effects on performance. Table 1 The pentosan and D-glucan levels (on DM basis) in Australian cereals from 1992. References Antoniou, T. and Marquardt, R.R. (198 1). Influence of rye pentosans on the growth of chicks. Poultry Science 60: 1989-l 904. . Choct, M. and Annison G. (1990). Anti-nutritive activity of wheat pentosans in broiler diets. British Poultry Science 31: 81 l-821. Gohl, B., Alden, S., Elwinger, K., and Thomke S. (1978). Influence of barley b-glucanase on the feeding value of barley for poultry and moisture content of excreta. British Poultry Science 19: 41-47. Recent Advances in Animal Nutrition in Australia: JuZy 1995 University of New England, Armidale NSW 23.51, Australia