Fiber and the Horse

Forages as hay or pasture make up the major share of the horse's daily intake. The energy and nutritive value of forages varies considerably and to a large extent is determined by the fiber content and fiber quality. Fibrous carbohydrates, also known as structural carbohydrates, are not digested in the small intestine but rather are digested by billions of bacteria in the hindgut. Some of the end products of bacterial fermentation include substances called volatile fatty acids (VFA) which are absorbed from the hindgut and used as a valuable source of energy. Feeds that contain structural carbohydrates are pasture, all types of hay, sugar beet pulp, soybean hulls and oat hulls.

Why is fiber beneficial?

  • Fiber provides a source of calories for horses.
  • Forage helps keep the gut full  
  • Fiber soaks up and holds water in the horse’s gut which acts a reservoir when horses need it.

There is not an exact requirement for fiber but diets that don’t provide enough fiber can cause major problems such as colic, dehydration, boredom and others.

Horses consuming pasture
ISU Horses Consuming Pasture

Horses should be fed a minimum of 1.5% of its bodyweight in fibrous feeds per day. This is equivalent to 1.5 lb./100 lb. bodyweight (equivalent to 15 lbs./day for a 1,000 lb. horse). At this level, horses can keep their gut full and have plenty of feed to chew on. Many horses will consume 2% of their bodyweight in forage per day. The type of forage used in horse feeding should be carefully selected so that appropriate levels of energy and nutrients are provided. Knowing the components of the forage or fibrous feed will allow an owner to feed the best grain mix to meet any deficits in the fibrous feed.