CEREALS have been fed to horses for generations; cereal grains are largely palatable, widely available and energy rich (due to their high starch content) making them a predictable feed choice for many horse owners for their hard working animals. The digestive tract of the horse is naturally suited to a forage or fibre diet. If starch is overfed, glucose derived from starch digestion may overwhelm the small intestine and pass into the hindgut where it can lead to dysbiosis (an imbalance of hindgut microbes), which can result in ill health such as colic, diarrhoea and laminitis. Cereals are used in the production of compound horse feeds and are also sold as straights, but they are not natural feeds for horses. The digestive tract of the horse is naturally more suited to a forage diet.

In nature, horses consume large quantities of fibrous pastures over the course of a 24-hour period. However, a horse with the high energy requirements of performance horse would not be able to meet their energy requirements consuming forage alone. This is why traditionally cereals and in the modern era compound feeds have become a component of all equine management systems.

Nutrient Deficiencies

All the cereals contain low levels of calcium and high levels of phosphorus. This is an important factor to correct. The protein quality is also low and in real terms cereals should be considered as simply a source of energy. If cereals are being fed as a straight they should be fed with a specific oat balancer, a feed formulated to balance the nutrient deficiencies found in cereals.

Cereals should always be fed with care, due to the high starch content. Unprocessed cereal grains are not very digestible, so they must be processed to convert them into a nutritious feed. This is because the outer portion of the grain (the hull) is designed to protect the seed from harsh environments. The hull is so effective that if the seed is consumed unprocessed, it can pass through the entire digestive system with little or no digestion.

The energy from starch is a fast release energy as starch is readily broken down to sugar in the small intestine where it is rapidly absorbed into the horses’ bloodstream. The raise in blood sugar following a cereal “meal” causes the insulin level to rise. These fluctuations in insulin are thought to have an effect on growth hormone in young horses which has been shown to affect the cartilage maturation process.

Processing cereal grains

Most grains should be processed before feeding. The purpose of mechanical processing is to break open the kernel so that once chewed and swallowed the digestive enzymes can access the starch for digestion. Mechanical processing does not improve digestibility much, whereas cooking methods of processing breaks down the starch molecules.

Oats

Oats have always been a very popular feedstuff for equines and we have a long farming tradition growing excellent quality native oats. Oats have a higher fibre content than other cereals making them safer to feed as they are less likely to be overfed and problems related to dysbiosis such as laminitis and colic are less likely. Oats are lower in digestible energy than maize and barley yet they have a higher raw starch digestibility. Oats may be lightly processed mechanically such as rolling, bruising or crushing although this does not increase the starch digestibility much, whereas cooking methods such as micronizing and extruding do.

Barley

Barley is a smaller grain with a harder outer covering than oats. It contains more digestible energy and less fibre than oats. Because the outer covering is hard, barley needs to be processed in order to break open the covering before it is fed to horses. Barley may be cooked, steamed, micronised or extruded; the purpose of all these processes is to make the starch more available and digestible to the horse.

Boiling barley was a common practice on farms over the years to supply working horses with an energy rich feed in winter months. Although this makes starch more digestible, this also destroys vitamins.

Maize

Maize, also known as corn, is higher in digestible energy than any other cereal grain. It is also low in fibre. It is more likely to be overfed and cause problems than oats or barley. Maize needs to be processed before feeding, usually by cracking, or micronising as the starch is difficult to digest in the small intestine. In an Irish context much of the maize available for feed manufacturing is imported; this combined with the requirement for rigorous processing makes this a very expensive raw material to include in diets.

Wheat

Wheat provides about 20% of human food energy and protein around the world. 10% of the world wheat grain production is used for animal feed and wheat ranks third among cereals used for animal feeding. Wheat bran and wheatfeed are wheat byproducts commonly found in equine diets.

Wheat has the same amount of digestible energy as maize and is also low in fibre. Wheat also contains a substance called gluten, which gives dough its elasticity. Wheat may form a dough ball type mess in the horse’s mouth particularly if ground wheat is fed. Wheat bran consists of the outer husk of wheat after the flour has been removed. This is a fibrous type material containing some protein with a poor (reverse) calcium to phosphorous ratio.