Foaling stalls are necessary for obtaining new eggs. Each stall holds one egg or foal, and becomes empty when its occupant grows up. A player must have at least one empty foaling stall in order to adopt, breed, or buy a new egg or foal. Eternal Youth sprites do not take up foaling stalls.
New players start with five foaling stalls, and may buy more from the Supply Depot for 10,000 silver each. The maximum number of stalls a user may own is 100, but five players have more, due to having bought them before the limit was enacted.
Foaling stalls are an important part of the game, and it is recommended to buy more to raise more foals at a time.