Collective name for carbohydrates are: starches, sugars, dietary fibre. The types of carbohydrates in an equine diet vary according to where in the intestinal tract they are absorbed, the speed in which they are absorbed and the amount of energy they provide. Every equine diet consists of varying proportions of the different types of carbohydrates. Adjustments are made according to the horse's requirements.
There are two types of CHOs: Structural, which consists of fibre, and non-structual, which consists of the sugars, starches and fructan.
Structural CHOs play a structural role in plants and are a major energy source to horses. The cell wall components are composed of cellulose, hemicellulose, pectin and lignin although lignin is not a CHO but closely related. Examples of typical feedstuffs that contain higher amounts of structural carbohydrates are pasture grasses, hay and haylage.
Structural CHOS are degraded by the large intestine by the intestinal flora, not digested in small intestine because the horse lacks the necessary endogeneous enzymes to breakdown the fibres. Therefore, structural carbohydrates travel pass through the small intestine to the large intestine.
Lignin is found in higher levels as the plant matures. This reduces the digestibility of the feedstuff.