Diet-induced thermogenesis in the prairie vole, Microtus ochrogaster

Diet-induced thermogenesis occurs in laboratory rats consuming either a cafeteria or a low-protein diet. Researchers suggest that diet-induced thermogenesis regulates weight by oxidizing excess food intake. Alternatively diet-induced thermogenesis may enhance nutrient uptake from a diet that is nutritionally unbalanced By increasing food intake and then selectively oxidizing excess nonessential nutrients, a herbivore could enhance uptake of one or more limiting nutrients. In the wild, nitrogen can be in limited supply for many animals, especially herbivores. The ability of a small herbivore to use diet-induced thermogenesis To enhance nitrogen uptake, therefore, could be adaptive. Prairie voles (Microtus ochrogaster) were studied to see if diet-induced thermogenesis occurs when they consume a low-protein diet. Results show that voles fed artificial low-protein diets (2.5% casein) have lower energy efficiencies and higher metabolic rates per unit of metabolizable energy intake than voles fed high-protein diets (15% casein), which is indicative of diet-induced thermogenesis. Herbivorous voles apparently require a lower level of dietary protein to elicit diet-induced thermogenesis than omnivorous laboratory rats. Also, voles are known to have a basal metabolic rate that is higher than predicted based on allometric comparisons to other vertebrates. Therefore, if is suggested that voles do not have to increase metabolism to oxidize excess intake until nitrogen levels are very low because their basal metabolic rates are already elevated and facilitate energy turnover and protein distillation in the body.