The Digestive Process of a Horse In the realm of science, horses are classified as animals in the opisthokont category of the unikont clade. Horses are mammals. They are non-ruminant herbivores or hindgut fermenters; this means that “their main and often exclusive food source is plants” (Huntington). This species has evolved over time to graze small amounts of roughage frequently throughout the day, typically 15-20 hours. Domestication has modified these feeding behaviors to fit keepers' schedules. Normally, people tend to feed large amounts of cereal once or twice a day. If people do not own a pasture where horses can graze, the animals are expected to eat large amounts of grass and/or alfalfa hay. This makes it much more difficult for horses to maintain their health because it undermines their abilities for proper digestion. It has been found that this problem can be solved by often feeding small quantities of feed to assimilate the natural grazing habits of the species. Horses “…have relatively small stomachs, holding only as much as a 5-gallon bucket of ice cream” (Reynolds). The stomach is physically capable of holding more substance than this, but it begins to empty as soon as it is two-thirds full. He performs this task as a safety precaution because they are unable to regurgitate food. Therefore, if they overeat or consume something poisonous, vomiting is not a possibility. The digestive system can be thought of in two separate sections; the first more similar to that of a human being, the second more precisely the rumen of a cow. Their small stomach has the potential to store two to four liters of substance for the average horse that is... middle of paper... going through. Adding oil to a horse's diet has been shown to slow the flow of feed through the small intestine; thus giving digestive enzymes more time to process starches, proteins and fats. In turn, this increases the total amount of nutrients processed into usable forms for horses and maximizes the digestive efficiency of the small intestine. Horses do not have a gallbladder. Because of this, it is difficult for them to digest and consume high-fat diets. They can handle about 20% fat in their diet, but it takes about three to four weeks to adjust to this change if the owner has not previously been consistent in this aspect of their diet. Normal rations in a typical horse's diet contain only about 3-4% fat. Also due to the lack of gallbladder, bile constantly flows from the liver into the small intestine.