An improved vertical feed mixer has a mixing chamber defined by a floor, a side wall, and an open upper end through which feed material, such as hay bales, is loaded into the chamber. A vertically disposed auger with tapered flighting is rotatably mounted within the chamber for cutting, mixing, and discharging the feed material through a discharge opening near the bottom of the chamber. A plurality of hay claws prevent hay from spilling over the top edge of the mixing chamber. The hay claws also catch the hay bales, or portions thereof, to inhibit rotation of the hay with the rotating auger, thereby allowing the knife blades on the auger to cut the hay. One or more plows are attached to the auger and extend between the flighting and the floor to direct material away from the auger shaft and thereby prevent feed material from becoming plugged. A plurality of grader blades extend outwardly from the auger shaft in close proximity to the bottom wall of the mixing chamber, thereby pushing mixed feed outwardly through the discharge opening a plurality of times during each revolution of the auger, thereby providing increased uniformity of the discharge flow of material into a feed bunk or trough.
