Processing biomass

A method of providing to an animal an electron beam irradiated, densified animal feed, the method comprising:

• changing the molecular structure of polysaccharides of a biomass comprising polysaccharides in the form of cellulose, hemicellulose, or starch, by exposing the unprocessed biomass to at least 5.0 Mrad of radiation provided by multiple treatments with one or more electron beam devices, where at least one of the electron beam devices operates at a power of at least 5 kW, to produce a processed biomass in which the polysaccharides have a number average molecular weight of from about 3,000 and 50,000 Daltons, the processed biomass having a nutrient availability of protein or amino acid, greater than the nutrient availability of protein or amino acid in the untreated biomass,
• wherein nutrient availability is determined by feeding equal amounts of the processed and unprocessed biomass to at least two distinct groups of one or more animals, and comparing fecal loss of protein or amino acid for the at least two distinct groups of one or more animals,
• densifying the processed biomass to produce an animal feed, and
• providing the animal feed to an animal for consumption by the animal.