Total C and N were measured by a flash elemental analyser (Thermo
Finnigan EA 1112 Series) at the Central Science Laboratory, University
of Tasmania, Hobart. Crude protein was calculated as N multiplied by
6.25. Protein was determined by a modified Lowry et al. (1951) method
(Houlihan et al., 1986), using approximately 20 mg of dry tissue. All biochemical
analyses were performed using analytical duplicates. The difference
between measured N (crude protein) and measured protein was used to estimate the non-protein nitrogen (a conversion factor of
6.25 was used throughout). The difference in N was calculated by dividing
protein by 6.25 and subtracting this from N (%) values to calculate
percent non-protein nitrogen as a percent of measured N.