On the relationship between chitin particle size and digestibility in the primate Galago senegalensis



Experiments were performed to examine the relationship between the particle size of chitin and its digestibility in the small insectivorous prosimian Galago senegalensis. In the first set of experiments, four animals were fed a 25% chitin diet with the chitin particles less than or equal to 60-mesh (0.250 mm maximum diameter). On average, the animals digested 22.5 ± 2.2 percent of the ingested chitin. In the second set of experiments, the four animals were fed a 25% chitin diet with the chitin particles ground to ≤ 40- and ≥ 45-mesh (between 0.425 and 0.325 mm). On average, the animals digested 2.75 ± 1.38 percent of the ingested chitin. There was no significant variation between the performance of any of the animals on either the 60- or 40–45-mesh trials. In all instances, however, each animal digested significantly more of the 60-mesh chitin and the 40–45-mesh chitin.

These experiments demonstrate the importance of masticatory efficiency among small mammals for improving the digestibility of foods such as insects which contain high proportions of chitin. They also suggest why insectivorous and folivorous primates have certain convergent dental specializations for finely grinding their foods. Both leaves and insects contain relatively indigestible structural carbohydrates. These substances are much more completely digested when the surface area to volume ratio of the swallowed material is increased. The masticatory efficiency of frugivorous primates is much lower since the constituents of these foods are relatively completely digested irrespective of the fineness of grinding.