A series of laboratory tests was conducted to understand the actions of crude cellulase extract from Trichoderma viride OM 9123 cultures. Enzyme units and specific activities within extracts within days were highly variable. These could be due to contaminations and the difficulty in standardizing the population of the micro-organisms inoculated into the bottles. Sixty-five percent ethanol was satisfactory as solvent for the isolation of crude cellulase for freeze-drying. corn cobs treated with high temperature and pressure, one percent sodium hydroxide and crude cellulase added to isonitrogenous and isocaloric grower rations produced pigs with better feed conversion efficiency compared to low fiber ration (control).