Chantaraj, 2000. Asian-Aust. J. Anim. Sci., 13 (Special issue): 27-34

There are many changes, both qualitative and quantitative, chemical as well as biochemical (enzymatic) in spent substrate during the growth and fructification of fruiting fungi. Depending upon the species/strain, culture condition, and substrate used the spent substrate is more soluble, contains 3- to 5-times more free sugar and 2- to 3-times more free amino acids than undegraded substrate. Decreases in cellulose, hemicellulose and lignin contents and increase in the ash content are concomitant. Certainly, these substrates possess a variety of degradatory enzyme like cellulase, hemicellulase, oxidizing enzymes and protease. Several applications of spent substrates are proposed, including sound use of this material in a sustainable agricultural system. The nutrients composition of substrate used during full spawn run, after harvest for 1 month, and spent substrate were analysed. Energy content, and most fat and fibre fraction percentages declined, while protein content rose in substrate of Pleurotus sp. but not of P. abalonus. Even though the substrate of Lentinus edodes has as good nutrient composition as the others it is not recommended as a substitute for commercial diet in growing quail ration. Spent substrate of P. ostreatus and Ganoderma sp. can replace up to 30% of the ration with no significant difference in growth performance. Most spent substrates can replace 10-20% of the ration, depending on species of fruiting fungi.