FIBER USE AND DIGESTION IN THE HERBIVOROUS RODENT OCTODON-DEGUS - AN ANALYSIS USING CHEMICAL REACTOR THEORY

Small herbivorous mammals compensate for high fiber food by ''fine-tun ed'' responses involving increases in gut volume and hence increases i n food turnover time and in the amount of energy obtained from fiber. By using models from chemical engineering adapted to digestion - i.e. chemical reactor theory - we attempt to understand the mechanisms of f iber hydrolisis and energy use as a function of the digestive design o f Octodon degus a small herbivorous rodent. These objectives were cond ucted taking into account the biotic environment, and specifically sea sonal changes in the intake of food differing in quality and fiber con tent. We postulated that during the environmental nutritional bottlene cks occurring in the dry season, O. degus may operate according to the principles of foraging and digestion theories. This small herbivorous seems to compensate for the low digestibility of high fiber food by i ncreasing gut volume contents and hence increasing food turnover time. A significant quantity of its daily energy requirements is obtained f rom the digestion of fiber from plants, as observed from the pattern o f fiber disappearance or reaction rate along the gut. The digestion an d reaction rate of high dietary fiber food may involve the acid condit ions of the stomach acting in concert with microbial ceacum fermentati on.