Nitrogen requirements of the didelphid marsupial Caluromys philander

The use of fruit-based diets by a small arboreal marsupial, the woolly opos sum (Caluromys philander) was studied to elucidate the mechanisms used to c ompensate for a low dietary protein concentration. The passage of a liquid phase digesta marker (Cr-EDTA) through the gut was significantly faster whe n animals were fed a diet containing 0.45% N compared to that measured on a diet containing 0.90% N. The size of the gut of the two groups was similar except that the caecum of animals fed 0.45% N was significantly larger tha n in those animals fed 0.90% N. Animals fed a diet of 0.45% N ate significa ntly more food than those fed higher levels of nitrogen but there was no si gnificant difference in the dry matter digestibility of the diet. The maint enance nitrogen requirement of the animals was 176 mg dietary N or 146 mg t ruly digestible nitrogen per kg metabolic body mass, with low losses of non -dietary faecal nitrogen being notable. There was no significant difference between diets in any measured parameter of urea metabolism and all animals recycled between 60% and 80% of the endogenously synthesised urea.