The present invention provides a method of making animal feed from lignocellulosic biomass. Biomass material having a moisture content of less than 30% is introduced into a pressure vessel. A vacuum is applied to the pressure vessel for at least one and preferably two minutes. Then steam is introduced to heat the biomass material to a temperature range of between about 180°C and 235°C where it is maintained for from 1 to 12 minutes before reducing the pressure in the vessel. In particularly preferred embodiments the moisture content is below 15% the temperature range is from 190°C to 215°C and the residence time is from 2 to 8 minutes.
