Then there is the matter of the large colon, with its sacculated construction that seems made to order for twisting or strangulating when the pouches become distended by gas during a bout with colic.
There is also the matter of length. If the horse’s entire digestive tract were stretched out end to end, it would measure nearly 100 feet. Despite this length, however, food travels through a horse’s digestive system quite quickly.
Harold Hintz, PhD, a member of the research staff within the Department of Animal Science at Cornell University in Ithaca, N.Y., says that when indicators (that show the speed of digestion) such as chromic oxide or colored particles are added to hay-grain diets, about 10% of the indicator is excreted within 24 hours; 50% within 36 hours, and 95% within 65 hours. The rate of passage is influenced by the type of feed ingested. Pelleted diets, for example, have a faster rate of passage than hay. Fresh grass also moves more rapidly through the tract than does hay.
In Mother Nature’s defense, she never planned for the horse to be domesticated and fed concentrates. Her plan was for the horse to be a grazing animal which would roam over the grasslands, consuming relatively small amounts of forage on a more or less steady basis. Thus, there was no real need for a stomach that could hold large quantities of food.
With that as perspective, it also makes sense to have a capacious hindgut (primarily the cecum and colon) that is the final staging area to break down roughage components and extract nutrients that had passed through the stomach and small intestine without being absorbed. It even makes sense for the cecum and large colon to have a sacculated structure because this tends to slow the passage of food through the area, thus providing more time for a breakdown of fibrous material through microbial activity.
It was man and his molding of the horse to fit a whole new order of life