The disclosure relates to a method of making an animal feed comprising treating a polysaccharide containing biomass with electron beam irradiation. In an exemplary embodiment of the disclosed method, biomass comprising polysaccharides in the form of cellulose, hemicellulose, or starch, is exposed to at least 5.0 Mrad of radiation, utilizing an electron beam operating at a power of at least 5 kW, to produce a feed material comprising a material having a number average molecular weight of from about 3,000 and 50,000 Daltons, the feed material having a nutrient availability of protein or amino acid greater than the nutrient availability of protein or amino acid in the biomass. wherein nutrient availability is determined by feeding equal amounts of the feed material and the biomass to at least two distinct groups of one or more animals, and comparing fecal loss of protein or amino acid for the two groups, and providing the feed material to an animal for consumption by the animal. Further embodiment’s relate to comminuted biomass being used as the feed-stock, the biomass having been dried to 5% or less moisture, cooling the biomass after irradiation followed by a second treatment with irradiation and further treating the biomass with enzymes.
