Abstract: An animal feeder having a feed trough and a feed hopper, located above the feed trough and having a discharge opening, for storing feed and dispensing feed through the hopper discharge opening to the feed trough. The animal feeder has a gate associated with the feed hopper which is movable through a range of positions to vary the size of the hopper discharge opening. The feeder is provided with a rotatable gate adjustment mechanism for changing the position of the gate and a gate support which includes a support member. The gate adjustment mechanism has a locking mechanism having an L-shaped stop member coupled to the gate adjustment mechanism. The stop member has two arms which are disposed substantially at a right angle.