Abstract: A venting device for an animal feeder which has a feeding teat is disclosed. The venting device has a chamber with an opening into the chamber. A vent opening is also connected to the chamber. A sealing element is retained freely moveable in the chamber. The sealing element has a first surface positioned relative to the opening such that, in use of the feeder, feed in the feeder will contact the first surface and cause the sealing element to move to a sealing position on seat to close the chamber from the vent opening. The surface is configured such that when a negative pressure in the feeder acts on the surface and is sufficient to overcome the weight of feed acting on the surface, the sealing element will be drawn into a position where the chamber can communicate with the vent opening and thereby vent the feeder to atmosphere.