Physiological mechanisms of foliage digestion in the greater glider and ringtail possum ( Marsupialia: Pseudocheiridae).

The diet of both the greater glider Petauroides volans and ringtail possum Pseudocheirus peregrinus is largely Eucalyptus foliage. Arboreal folivores appear to have low field metabolic rates (ie low total energy requirements) and therefore low feed intakes. These are adaptations advantageous to animals feeding on tree foliage which is generally of low nutritive value. Low feed intakes also mean that the ingestion of secondary compounds (xenobiotics) such as essential oils and phenolics is minimised. Both pseudocheirids are hindgut fermenters, with a large caecum. The rate of passage of digesta through the gut is slow, and fluid digesta (along with the fine particles) are selectively retained in the caecum, the less digestible coarse particles being eliminated relatively rapidly. The ringtail possum is coprophagic, or more specifically caecotrophic (ie soft faeces of high nutritive value derived from caecal contents are ingested form the cloaca). Caecotrophy increases the mean retention time of fluid digesta, maximises the digestibility of fibre in fine particles, and salvages caecal microbial products such as B-vitamins and protein. The maintenance N requirement of ringtail possum is thereby much lower than that of the non-coprophagic greater glider.-from Authors