Horses evolved to eat a lot of fiber, spending up to 17 hours a day grazing various forage plants. But not all fiber is created equal, especially when it comes to hay.
Hay carries a few challenges compared to living forages. One, compared to fresh forage, dry hay lacks the moisture needed to move fiber along the digestive tract. Unlimited access to fresh clean water is essential when feeding a lot of hay, as impaction colic can result if the hay is too high in fiber, says Kathleen Crandell, PhD, an equine nutritionist with Virginia Tech's Middleburg Agricultural Research and Extension Center. She also says if bulky hay is too high in fiber (as in very mature hays), horses will fill up on the hay, but in doing so might not consume enough calories to maintain body condition if they are hard keepers or hard-working horses.
So what's the right amount of fiber? There are two measures of fiber in forages that can give the owner an idea of fiber content and forage quality. Horses need a combination of fiber types to maintain digestive tract health.