Gastrointestinal tract
The small intestine begins at the duodenum and is a tubular structure, usually between 6 and 7 m long. Its mucosal area in an adult human is about 30 m. Its main function is to absorb the products of digestion (including carbohydrates, proteins, lipids, and vitamins) into the bloodstream. There are three major divisions:
Equine nutrition
The small intestine is long and holds to . This is the major digestive organ where 50 to 70 percent of all nutrients are absorbed into the bloodstream. Bile from the liver acts here, combined with enzymes from the pancreas and small intestine itself. Equids do not have a gall bladder, so bile flows constantly, an adaptation to a slow but steady supply of food, and another reason for providing fodder to horses in several small feedings.