Moisture was determined by oven-drying method at 105 ± 1 C. Fat was measured in a Soxhlet system by extraction with diethyl ether solvent. Total nitrogen content was analysed by the Kjeldahl procedure. The conversion factor used to transform nitrogen into protein was 5.71. Ash content was determined by incineration of samples at 550 C in a muffle furnace (James, 1995).