Animal-activated feeding systems and methods. The systems include a self-sealing valve assembly that, responsive to activation of a feed-flow activation member by an animal, selectively delivers a flow of the liquid feed to a vessel for consumption by the animal. The valve body further includes a valve member, which is configured to selectively obstruct the feed flow path, and a feed-flow activation member coupled to the valve member. The feed-flow activation member and valve member are selectively positionable between at least a sealed position and a range of activated positions. The valve assembly may include a buoyant activation restriction member adapted to restrict at least further or subsequent activation of the valve assembly responsive to the level of liquid feed in the vessel. The valve assembly may be configured to dispense the feed in a confined stream and/or in a generally horizontal or lateral direction into the vessel.