The ammonia fiber explosion (AFEX) process, previously run only in a batch reactor, has been adapted to run on a twin-screw extruder. The sugar yield of AFEX material after enzymatic hydrolysis has been increased up to 3.5 times over that of completely untreated material. The ruminant digestibility of corn fodder has been increased up to 32% (from 54-71%) over completely untreated material, and 23% (from 63-77%) over material extruded with no ammonia. Extrusion-treated material proved more digestible by the ruminant at 48 h than material treated in the batch reactor.