Digestive-Tract Function and Energy-Requirements of the Rufous Hare-Wallaby, Lagorchestes-Hirsutus

Abstract

Digestive performance and rate of passage of fluid and particulate markers through the gastrointestinal tract were measured in captive rufous hare-wallabies (Lagorchestes hirsutus) maintained on a commercial pelleted diet. This diminutive (0.8-2.1 kg) marcropodid marsupial was found to have a large, basically tubiform forestomach (tubiform forestomach 71-74% of total stomach capacity), similar to that of the large grazing kangaroos and markedly different from those of small browsing wallabies and similar-sized rat-kangaroos. This 'kangaroo-like' gastric morphology, together with a low maintenance energy requirement (326 kJ digestible energy kg-0.75 day-1) and thus low food intakes (33 g dry matter kg-0.75 day-1) and long mean retention times of digesta in the gut (23 h for a fluid marker, 38 h for a particle marker), were considered to be major factors in the ability of this small arid-zone herbivore to digest fibre (50% of the neutral-detergent fibre and 31% of the acid-detergent fibre of the pelleted diet) and thus to utilise plant material that is often of low quality in the Tanami Desert.