Digestive physiology of captive giant anteaters (Myrmecophaga tridactyla): determinants of faecal dry matter content

Abstract

Giant anteaters (Myrmecophaga tridactyla) are specialized insectivores and consume mainly ants and termites in the wild. In captivity, giant anteaters are either fed a complete diet, or a combination of a domestic carnivore diet with leaf eater pellets, or a traditional gruel-type diet. Soft faeces are a frequently encountered problem with this type of feeding. In the present study, we analysed diet and faeces composition, calculated digestibility and measured mean retention time on various diets in eight giant anteaters (total of n = 64 experiments). The results suggest that the digestive physiology of giant anteaters is similar to that of domestic dogs and cats in terms of nutrient digestibility and digesta retention. When testing correlations between faecal dry matter content and other variables, no relationship with dietary crude fibre content or mean digesta retention time could be detected. However, acid insoluble ash intake was significantly and positively correlated with faecal dry matter content. The amount of acid insoluble ash excreted with the faeces was higher than that ingested with the diet offered, indicating that the giant anteaters ingested soil from their enclosure of up to 93 g per day. This finding is consistent with observation of faeces of wild giant anteaters that contain soil or sand most likely due to indiscriminate feeding. It also corresponds to reports that indigestible materials such as peat, soil, chitin or cellulose contribute to a firmer faecal consistency in various carnivore species. Therefore, offering giant anteaters the opportunity to voluntarily ingest soil from their enclosure might be beneficial.

Acidic mammalian chitinase gene is highly expressed in the special oxyntic glands of Manis javanica

“…In most cases, the hard cover polysaccharide chitin of insects accounts for 5-20% of their dry weight [8] and may be an important component of the pangolin daily diet. However, the health of pangolins improves when additional chitin is included in their diet [9], similar to findings observed in giant anteaters (Myrmecophaga tridactyla) [10,11], thus suggesting that their gastrointestinal (GI) tract is highly adapted to chitin digestion. This observation also led us to ask whether M. javanica can actually digest chitin or whether it simply serves as dietetic fiber.…”

Digestibility of a new diet for captive short-beaked echidnas (Tachyglossus aculeatus)

“…In captivity, replicating the diet of free‐ranging echidnas is problematic, because of difficulties providing adequate quantities of ants and termites for food. Captive diets used for echidnas, and for other myrmecophagous species, often include some of the following: raw meat, eggs, bran, vegetable oil, wheat germ and cat or dog food mixed together with water and vitamin and mineral supplements [Jackson, ; Augee et al, ; Gull et al, ; Lin et al, ]. Generally the mixture is presented as slurry to cater for the specialized anatomy of the echidna bill.…”

“…Generally the mixture is presented as slurry to cater for the specialized anatomy of the echidna bill. Unusually soft feces are observed in captive myrmecophages and this reflects diet consistency, possible bacterial contamination [Morford and Meyers, ] and/or the lack of dietary indigestible material [Gull et al, ]. Thus, diets incorporate soil or plant material such as peat, and/or chitin to help firm feces [Morford and Meyers, ; Steinmetz et al, ].…”

“…Some captive myrmecophages, including Chinese pangolins ( Manis pentadactyla ) and giant anteaters ( Myrmecophaga tridactyla ), have been transitioned to new manufactured diets in captivity with mixed success [Gull et al, ; Lin et al, ]. The aims of the study were to: (1) transition captive short‐beaked echidnas over to a new insectivore diet; (2) determine digestibility and palatability of the new manufactured diet; (3) test the efficacy of using fiber instead of soil in the diet.…”

Aspects of digestive anatomy, feed intake and digestion in the Chinese pangolin (Manis pentadactyla) at Taipei zoo

“…Stomach structure was as previously reported by Imai et al [1973]; the very muscular stomach sometimes contains gravel and grit which may assist with digestion , in much the same function as a gizzard. Quantitative data on the actual occurrence of soil in the gastrointestinal tracts of ant-and termite specialists, however, or its impact on digestive physiology, are limited and details remain to be investigated (see Gull et al, [2014] for a more detailed discussion of this topic). As opposed to observations in M. pendatactyla, no keratinous spines have been reported in the stomachs of M. gigantea, M. tetradactyla, or M. tricuspis [Krause and Leeson, 1974]; this appears to be a true difference between Asian pangolins and African pangolins.…”