An herbivore is an animal that eats plants. Most livestock that eat plants have a large vat called a rumen that ferments the vegetation before it enters the rest of the digestive tract. However, horses are unique in that they eat plants but do not have a rumen like cows - horses have a simple stomach. Horses are able to digest plants because they have a cecum, which is also a fermentation vat. The difference is that in horses the cecum is close to the end of the digestive tract, unlike animals with a rumen where the cecum is at beginning of the digestive tract. Because of this design, Dr. Karen Davidson with Purina Feeds indicates horses evolved as continuous grazers that grazed small, immature, easily-digested plants and were allowed unlimited free range grazing.
Unfortunately, this scenario is not possible for most of today’s horse owners as most horses are kept in small areas and fed twice daily. The reason we see so many colic and founder cases is because horses are being fed in a manner that their body was not designed to support. And although there is not a lot we can do about this, as we certainly can’t turn all the horses out on the open range, it is important to realize the ideal management for horses and try to mimic this as closely as possible. For instance, you can see why it is important to keep horses out of stalls. Also, it is important to give them small amounts of feed as often as possible instead of feeding large amounts of hay and feed once daily. Although frequent feeding may be more difficult for you and take more time, you can see why it is more natural for the horse and may prevent colic. If you have questions about your horse’s nutrition, ask your equine veterinarian, who is your nutritional expert.