Horses are ruminants

The cow in the horse: Horses chew in a similar way to ruminants

Herbivores are better able to utilize their hard-to-digest food if it is severely chewed through intensive chewing. In ruminants such as cows, sheep, goats, deer, llamas or camels, eating and ruminating are two different processes: After grazing, they choke up larger parts of their food and chew it again with particularly uniform, rhythmic movements. In this way they achieve the highest degree of shredding of their food.

Researchers from the University and ETH Zurich now looked into the question of whether the chewing movements of ruminants with each other and with those of other herbivores are comparable. In their study with horses, cows and camels, they used special chewing halters that register the movements of the mouth and can automatically differentiate between chewing and ruminating.

The horse showed an unexpected result. "To our surprise, the evaluation software showed that the horse did not eat, but chewed on it, so to speak," says Marie Dittmann, doctoral student at the University of Zurich and the ETH Zurich. "Although horses are not ruminants, they chop up their food with chewing strokes that are just as rhythmic as the cows do when they chew."

For Marcus Clauss, professor at the Clinic for Zoo, Pet and Wildlife Animals at the University of Zurich, the similarity in the chewing rhythm of such different animal groups is understandable: “Horses don't have a second chance to chop up something that is difficult to digest. Therefore, they have to chew very thoroughly as they eat. Obviously, this works best with rhythmic and steady movements.