Mixer (1, 1', 40) for feed, provided with at least one auger and at least one gearbox (8a, 8b, 9) with an input drive shaft (10) and an output shaft (16) for driving the auger. The mixer comprises means (29, 35, 41, 44), such as a fan, for generating an air flow along the gearbox. The gearbox can for instance comprise a right-angle gearbox with or more planetary reduction gearboxes.