Changes in gut dimensions and capacity of Peromyscus maniculatus relative to diet quality and energy needs

Abstract

Deer mice were maintained on diets diluted with 25, 30, and 45% fibre at 20 °C and on diets of standard laboratory chow at 20, 15, 10, and 5 °C to determine the effects of decreased diet quality and increased energy requirements on the dimensions of the alimentary tract. Weight of the small intestine with contents and of the caecum with contents showed the greatest responses to decreasing diet quality. These increased 59 and 61%, respectively, when diet contained 45% cellulose. Weight of the small intestine with contents showed the greatest response to increasing energy requirements by increasing 96% when temperatures were reduced to 5 °C. However, all weight and length measurements increased with both increased energy demands and decreased diet quality. Weight of the intestinal tract with contents provides an indicator of daily food intake, but the gross dimensions of the alimentary tract cannot be used to differentiate between energy requirements and diet quality.