The conversion of straw into feed by basidiomycetes

Abstract

1. The solid-state fermentation of straw byPleurotus cornucopiae, Pleurotus sp. Florida, Agrocybe aegerita, andStropbaria rugosoannulata at 22°, 25°, and 30°C during 0–120 days was examined. 2. During the first stage of fungal growth (saprophytic colonization), the quantity of water soluble substances, reducing sugars, and in vitro digestibility of the straw-fungal myeelium mixture decreased. 3. After 20 days, the amount of water soluble substances and reducing sugars increased. Temperature strongly influenced the rate of substrate decomposition, particularly with cultures ofPleurotus cornucopiae andStropharia rugosoannulata. 4. Of the fungal cultures examined,Pleurotus cornucopiae andStropharia rugosoannulata showed the highest rate of straw decomposition and released the greatest amount of metabolic energy from the straw. 5. The heat of combustion of decomposed substrate decreased due to increasing ash content and varying degree of metabolism of cellulose and lignin. 5. The in vitro digestibility of wheat straw was strongly influenced by incubation temperature and increased during fermentation byPleurotus species andStropharia rugosoannulata. 7. Agrocybe aegerita exhibited good properties for production of fruiting bodies, but this species was not satisfactory for the conversion of plant residues to feed.Stropharia rugosoannulata, however, increased the digestibility of straw by 31.6%. 8. Some technical possibilities for using fungi for upgrading waste straw to animal feed are discussed.