Effect of dietary cellulose on the metabolic activity of the rat caecal microflora.

Alpha-cellulose, added to a purified diet at six levels [0%, 2.5%, 5%, 10%, 20%, and 40% (w/w)] and fed to weanling rats for 3 weeks, had no effect on body weight, but it increased the weight of caecal contents and decreased the numbers of bacteria per total caecal contents. Caecal microbial azoreductase, nitroreductase, beta-glucosidase and nitrate reductase activities per total caecal contents were also significantly decreased by 10% dietary cellulose and above, yet beta-glucuronidase activity was only affected significantly by 40% dietary cellulose. Azoreductase and nitroreductase activities were highly correlated with one another and showed a similar response to cellulose.