Abstract: Proteinaceous raw materials, possibly mixed with starchy raw materials are extruded into an expanded dry feed or foodstuff by extruding a starting mix with at least 12 but not more than 20 percent by weight of moisture in a short time, while keeping the extruder permanently filled with raw material mixture. Preferably not more than 7 percent of fat should be present. The inventive apparatus for extruding this material has grooves in the extrusion casing extending in longitudinal direction, and the extrusion screw ends at the outlet side in a nose cone. Preferably one pitch length is present between a screw seal and the feed inlet, and also one pitch length is present between the feed inlet and a compression section of the screw.