In an apparatus for feeding animals including one or more feed dispensing containers from which the animals can take feed which are fed by supply ducts from a supply a device is provided which includes a feed supply duct portion arranged such that the feed falls through the feed supply duct portion under gravity. A drive member is mounted at the duct and includes a plurality of paddle blades of a wheel mounted for rotation about an axis of the wheel such that falling feed in the duct acts to drive the blades to rotate the wheel about the axis and a driven component driven by the wheel. The driven component is in most cases a dispenser for feeding a liquid or particulate additive material from a supply cartridge, which is mounted on a common housing forming the duct and containing the wheel, to an injection opening on the bottom of the housing for addition to the feed passing through the duct portion.
