Effects of Dietary Fiber on Gut Retention Time in Captive Macaca cyclopis, Macaca fascicularis, Hylobates lar, and Pongo pygmaeus and the Germination of Ingested Seeds
Gut retention time (GRT) defined as the time needed for seeds to pass the digestive tracts of consumers, can affect the germination rates of ingested seeds. GRT can vary with the amount of dietary fiber consumed by primates. We investigated how dietary fiber affects GRT in captive individuals of four hindgut fermenting primate species: macaques (Macaca cyclopis and Macaca fascicularis) gibbons (Hylobates lar) and orangutans (Pongo pygmaeus) We used Hylocereus undatus seeds as markers to measure GRT in each species when fed high (18 22% and low (14 16% fiber diets. We also examined the effect of GRT on seed germination in Ficus septica and Trema orientalis (germination time: mean SE 10.4 0.3, 86.9 2.5 days, respectively) by comparing these seeds with the pulp removed, as a control. We found that GRT was longer when gibbons and orangutans fed on a high fiber diet than on a low fiber diet, but this was not the case for macaques. The percentage germination of ingested F. septica seeds was lower and germination time was longer than the control. T. orientalis seeds were less likely to germinate than control seeds were but did so more quickly if they did germinate after passing through M. cyclopis and P. pygmaeus. GRT decreased the germination rate of seeds of F. septica, but not seeds of T. orientalis. Together our results suggest that the effect of dietary fiber on GRT differs among primate species, and that the effect of such differences in GRT varies with the seed species they swallow.
International Journal of Primatology