Relative merits of using purified proteins and natural foods in studies of wildlife nutrition: the nitrogen requirements of a rodent pollinator

Aethomys namaquensisis a 60 g murid rodent that is an important pollinator of several Protea species in South Africa. We compared the nitrogen requirements of this species on two different protein sources: pollen and casein. Pollen is an important source of nitrogen for specialist flower-feeding mammals in Australia. However, its value for a generalist rodent species such as A. namaquensis had not previously been assessed. Casein is often used as the source of protein protein makes it easier for researchers to compare their results with those from other studies. The apparent digestibility of casein was significantly higher than that of pollen, 75.6 % vs 58.4 %, but the biological value was significantly lower, 39 % vs 49 %. As a result of the lower biological value the truly digestible maintenance nitrogen requirements of