The effects of plant and tooth structure on intake and digestibility in two small mammalian herbivores.

We investigated the interaction between plant structure and animal tooth structure and how it can affect digestive performance in two small mammalian herbivores. Mastacomys fuscus, an exclusively herbivorous rodent, and Rattus lutreolus, a less herbivorous rodent, were fed diets varying in fibre structure and level (18%-45% neutral detergent fibre). On high-fibre whole wheat diets, R. lutreolus was not able to maintain body mass. M. fuscus was able to maintain body mass, and this was related to a much greater intake by M. fuscus on this diet. We attribute this result to more effective physical processing by M. fuscus as a consequence of a highly developed dentition. On a milled-wheat diet, intake by R. lutreolus increased significantly compared with the whole wheat diet, although intake was still not great enough to maintain body mass. On diets that were lower in fibre than the wheat diet, and with different fibre arrangements, R. lutreolus was able to achieve intakes great enough to maintain body mass. This suggests that, in addition to gut constraints, the physical form of the plant diet and dental structure can have a significant effect on digestive performance by animals in feeding trials.