Fungal protein produced on cassava for growing rats and pigs

This research is a nutritional assessment of a fungal (Aspergillus fumigatus 1-21A) single-cell protein (SCP) that was fed to rats and pigs. The sun-dried biomass resulted from fermentation of either fresh roots or cassava meal substrates and had the following percentage composition: crude protein (N x 6.25), 34.3; ether extract, 3.1; crude fiber, 20.0 ash, 4.3; N-free extract, 27.9; Ca, .20 and P, .79. The gross energy was 4,260 cal/g. An initial biological evaluation based on protein efficiency ratio (PER) and net protein ratio (NPR) methods was conducted using 70 growing rats. Growth responses in rats fed the dried product were similar to those produced by the casein control, provided the biomass was supplemented with DL-methionine. During the growing-finishing period (15.8 to 95.0 kg), pigs were given one of the following experimental diets: 1) control, sorghum + soybean meal (SBM), 2) cassava meal (CM) + SBM + .3% DL-methionine, 3) CM + SCP and 4) CM + SCP + .3% DL-methionine. Diets were calculated to supply 16 and 13% crude protein for the growing (15.8 to 50 kg) and finishing (50 to 95 kg) periods, respectively. The pigs fed the diet based on SCP without any methionine took longer (P<.05) to reach market weight and had poorer (P<.05) feed conversion than pigs fed the other diets. Supplementation with DL-methionine improved (P<.05) the nutritive quality of the fungal protein and the results were comparable to those obtained with diets based on SBM. The use of SCP as a total substitute for SBM did not affect the normal physical condition of the animals.