Exploiting a readily available but hard to digest resource: A review of exudativorous mammals identified thus far and how they cope in captivity

Abstract

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 to access the energy it possesses. Gums are 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 the context of their evolutionary adaptations. We also investigated the recommended captive diets for these species to look at whether gum is recommended. We conducted a literature search on ISI Web of Knowledge to tabulate all mammal species observed ingesting gum and classified them as obligate, facultative or opportunistic feeders. We encountered 94 mammal species that eat gum in the wild (27 obligate feeders, 34 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.

The Gut Microbiome of Exudivorous Marmosets in the Wild and Captivity

“…The GMC of captive and translocated marmosets shows similarity to certain aspects of the GMC of human GI diseases associated with gut microbiome dysbiosis [7,18,73,74]. Crohn's Disease (CD)…”

“…A number of mammals are exudivorous [16], particularly primates [18], but their gut microibome remains less studied relative to other mammals. However, the Brazilian Callithrix marmosets, obligate NHP exudivores, are excellent models to improve our understanding of exudivore gut microbiome.…”

Identification of possible nutritional and stress risk factors in the development of marmoset wasting syndrome

“…However, Brack and Rothe () found that such a high level of protein may not be required but rather, the high 25% protein requirement for this species may have stemmed from fear of MWS. Cabana et al () compiled the chemical information of gums eaten by wild exudativorous mammals, most notoriously marmosets and slow lorises ( Nycticebus spp.). The average crude protein (dry matter) concentration of tree gums is 4.5% and pod gums (more often ingested by tamarins rather than marmosets) is 7.4% (Cabana, Dierenfeld, Wirdateti, Donati, & Nekaris, ).…”

“…Both are expected to be high in magnesium, with insects also being higher in potassium and zinc (Finke & Oonincx, ). However, with less than 30% of foraging time being spent on insects (Cabana et al, ), the magnesium and zinc content of wild insects would be somewhat diluted by the ingestion of fruits, plant parts, and gum. This is necessary to balance the nutrient concentrations to acceptable amounts, as a diet too high in insects (or concentrates) may have inappropriate concentrations of certain nutrients.…”

“…). However, with less than 30% of foraging time being spent on insects(Cabana et al, 2018), the magnesium and zinc content of wild insects would be somewhat diluted by the ingestion of fruits, plant parts, and gum. This is necessary to balance the Trichospirura leptostoma (pancreatic worm), Prosthenorchis elegans (thorny-headed worm), amoebiasis, Enterobius vermicularis (human pin worm), Primasubulura jacchi (pinworm), Platynosomum (adult flukes) are other proposed triggers for MWS…”