A pig feeder of the type comprising an inverted trapezoid-shaped hopper in which the supply of feed-to-be-dosed is loaded, which is easy to adjust by means of a single control unit that acts at the same time on both edges of the lower tray, which serves as an adjusting feed dosing gate, for which purpose a synchronism bar is provided in the upper part, which further enables an accurate readout of the dosing aperture position of the feeder by means of a rotating pointer.