Evaluation of Short-Chain Fatty Acid Production in the Cecum of Fiber Fed Rats

Abstract

Short-chain fatty acid (SCFA) production rate in the cecum was estimated by the in vitro incubation system of the cecal content collected immediately after sacrifice, and compared with the SCFA content in the cecum under various conditions in rats. The cecal contents were anaerobically incubated at 37 °C for 1-4 hr. The initial concentration (SCFA content) and the increment of the each SCFA concentration after the incubation (SCFA production rate) were increased by fiber feeding. But, the proportions of the larger SCFA contents in the total SCFA were smaller than those of the production rates. We also observed that the SCFA content and production rates changed diurnally in rats fed guar gum, but the variation profiles of the SCF A content in the cecum were different from those of the production rates. Neomycin feeding clearly decreased the SCFA production, but not the contents in the fiber fed groups. The production rate reflects the in vivo digestible energy of dietary fiber sources measured by fecal excretion of fiber energy. These results reveal that the short time of the in vitro incubation of the cecal contents was a simple and useful method for the evaluation of the in vivo SCF A production rate from ingested dietary fibers, and that the contents of SCF A in the cecum did not usually reflect the SCFA production rate.