Abstract: Rural biomass and other cellulosic materials are converted to a protein-enriched animal feed supplement or to single-cell protein by a series of bio-reactions. A first stage bio-reaction is a solid substrate bio-reaction. Enzymes, such as cellulase, produced by the first-stage bio-reaction are added to a second-stage bio-reaction. Raw second-stage bio-reaction feedstock is pretreated to hydrolyze hemicellulose and/or to partially digest starch in the feedstock. In the second-stage bio-reaction, the feedstock is substantially digested and single-cell protein is harvested in an aerobic bio-reaction, while ethanol is produced in an anaerobic reaction. Alternatively, raw biomass or other cellulosic materials can be treated with organic acid (e.g. maleic acid) combined with dry steam to produce a nutritional product that can be directly used as an animal feed supplement.

Abstract: Rural biomass and other cellulosic materials are converted to a protein-enriched animal feed supplement or to single-cell protein by a series of bio-reactions. A first stage bio-reaction is a solid substrate bio-reaction. Enzymes, such as cellulase, produced by the first-stage bio-reaction are added to a second-stage bio-reaction. Raw second-stage bio-reaction feedstock is pretreated to hydrolyze hemicellulose and/or to partially digest starch in the feedstock. In the second-stage bio-reaction, the feedstock is substantially digested and single-cell protein is harvested in an aerobic bio-reaction, while ethanol is produced in an anaerobic reaction. Products of the invention can serve as feed supplements to enhance protein content of animal feed.