Exploiting A Readily Available But Hard To Digest Resource: A Review Of Exudativorous Mammals Identified Thus Far And How They Cope In Captivity

Gum is a widely available carbohydrate, composed mainly of non-digestible structural carbohydrates. No mammalian enzymes can digest gum, therefore a mammal ingesting gum must rely on microbial fermentation in order to access the energy it possesses. Gums are known as relatively nutrient poor. Despite this, some mammals have evolved to exploit this food resource. We aim to review the literature for all mammal species which have been recorded to ingest gum, whether quantified or not and discuss this in context of their evolutionary adaptations. We also investigated the recommended captive diets for these species to look at if gum is recommended. We conducted a literature search on ISI Web of Knowledge to tabulate all mammal species observed ingesting gum and classify them as obligate, facultative or opportunistic feeders. We encountered 94 mammal species which eat gum in the wild (26 obligate feeders, 35 facultative feeders and 33 opportunistic feeders). Obligate feeders have entirely evolved to exploit this resource but were found to not be given gum in captivity, which may explain why they are failing to thrive, as opposed to facultative feeders which have fewer issues. Gum may be necessary for the health of obligate feeders in captivity. Future research should focus on the physiological effects that gum ingestion poses on different digestive systems. This article is protected by copyright. All rights reserved