Retention marker excretion suggests incomplete digesta mixing across the order primates

Publication date: Available online 21 May 2019Source: Physiology & BehaviorAuthor(s): Ikki Matsuda, Fabiola C. Espinosa-Gómez, Sylvia Ortmann, John C.M. Sha, Ismon Osman, Joeke Nijboer, Angela Schwarm, Takayoshi Ikeda, Marcus ClaussAbstractThe digestive tract of animals, and the patterns how passage markers are excreted from them, have been fruitfully compared to chemical reactor models from engineering science. An important characteristic of idealized reactor models is the smoothness of the curves plotting marker concentrations in outflow (i.e., faeces) over time, which is the result of the assumed complete mixing of the marker with the reactor contents. Published excretion patterns from passage experiments in non-primate mammals appear to indicate a high degree of digesta mixing. In order to assess whether marker excretion graphs from primates differ from ideal outflow graphs, we performed passage experiments in eight individuals of three foregut-fermenting species (Pygathrix nemaeus, Trachypithecus auratus and Semnopithecus vetulus), and added them to available marker excretion curves from the literature. In the resulting collection, 23 out of a total of 25 patterns in foregut fermenters (21 individuals of 10 species from 7 studies), and 13 out of 15 in hindgut fermenters (9 individuals of 2 species from 2 studies), showed an irregular, ‘spiky’ pattern. We consider this proportion to be too high to be explained by experimental errors, and suggest that this may indicat...
Source: Physiology and Behavior - Category: Physiology Source Type: research