Difference in Composition Between Crude Fiber and Acid-Detergent Fiber

Abstract

Abstract When crude fiber content of feces, silage, and pellets was determined by the AOAC and acid-detergent methods, the ADF method invariably yielded higher results. Differences between methods varied directly with lignin content of original materials and were most pronounced in feces. Regression equations would not provide acceptable AOAC values from determined aciddetergent fiber (ADF), especially in feces. Crude fiber was isolated from above materials by both methods and analyzed for lignin, pentosans, and cellulose. ADF contained more lignin but less pentosans and cellulose than the AOAC fiber. Differences in pentosan content were smallest. Cellulose content of the fibers varied inversely with the lignin content. ADF retained virtually all lignin and cellulose bvit lost 82— 84% of original pentosans. AOAC fiber retained original cellulose but lost 60—84% of original lignin and 80—86% of original pentosans. The retention of cellulose and the loss of pentosans by both methods are not consistent with animal digestive studies.