Horse and cow breeding and chickens

Foals can sleep in a stall with one of their parents. When they age up, they'll need a stall of their own, if you want them to use one. But horses can sleep outdoors and eat grass, and drink from an outdoor watering trough or a pond, except when it freezes in the winter, so they don't have to each have one of their own. I prefer to have one for each horse, so long as my sims can afford it, though if there's plenty of room in the barn, they can still sleep inside without a stall.