Nitrogen and Urea Metabolism and Nitrogen Requirements of the Common Ringtail Possum, Pseudocheirus Peregrinus, Fed Eucalyptus Andrewsii Foliage.

Abstract

The maintenance nitrogen requirement of mature common ringtail possums, Pseudocheirusperegrinus, feeding on a sole diet of Eucalyptus andrewsii foliage was estimated to be 380 mg.kg-0.75.d-¹ on a dietary basis and 290 mg.kg-0.75.d-¹ on a truly digestible basis. The difference between these two estimates was due to a low true digestibility of nitrogen of 79%. Apparent digestibility of nitrogen was 58%. The level of urea metabolism in the ringtail was low compared with other herbivores. Only 40 mg urea-nitrogen.kg-0.75 was recycled to the gut each day, but this was 96% of irreversible loss rate (i.e. endogenous synthesis rate) and 11% of the ringtail's intake of truly digestible nitrogen. A low maintenance requirement for nitrogen, together with the recycling of a high proportion of endogenous urea to the gut, helps to explain the ability of the ringtail possum to remain in positive nitrogen balance on a sole diet of E. andrewsii foliage of only 1.1% nitrogen content.