* Horses are designed to eat hay: Hay is a natural part of their diet, and they have digestive systems perfectly suited to breaking it down.
* Fresh hay doesn't stink: High-quality, dry hay doesn't have a strong odor.
* Spoiled hay smells: If hay gets wet, moldy, or starts to decompose, it will definitely smell bad. Horses won't eat it if it smells bad.
So the answer is: A horse will eat hay as many times as it wants, without it smelling bad, as long as the hay is fresh and of good quality.