Horse Nutrition & Feeding

Pony Club pony.Feed according to work is one of the golden rules of feeding - a child’s pony fed on oats would quickly become unmanageable whereas a racehorse fed only on grass could not be expected to win races. Providing a horse with the correct diet is essential if he is to perform and behave as we expect.

Understanding the horse’s nutritional requirements and how different feeds supply these needs allows an appropriate diet to be chosen for each horse.

Nutritional requirements

In order to survive a horse needs six types of nutrient: carbohydrates, fats, protein, vitamins, minerals and water. The quantity of each of these required by a particular horse will depend on his age, temperament and the type of work he is doing.

Carbohydrates are the main source of energy for a horse. Energy is needed for all bodily functions including breathing, moving, eating and growth. Soluble carbohydrates like sugar and starch are broken down into glucose in the stomach and small intestine and absorbed into the bloodstream for use as energy throughout the body. Grass is a source of sugar and in spring can contain as much as 20%. Cereals are abundant in starch, making up about 40% of oats and 70% of maize.

Insoluble carbohydrates like fibre (cellulose) cannot be broken down by enzymes which the horse produces itself. The horse relies on the microbial population in the large intestine to produce the necessary enzymes to ferment the fibre and release volatile fatty acids. Fibre gives a slow release of energy (which also generates a significant amount of body heat so is particularly important in winter) whereas sugars and starch provide an instant energy source. Fibre is abundant in all plants.

Although oats provide less energy than other cereals they do tend to make some horses fizzy. Oats can be used for up to 90% of the concentrate ration. Barley has a higher energy content than oats so is a good conditioning feed but it needs to be processed to make it digestible. It also has a low fibre content so should not make up more than 50% of the concentrate ration. Maize also has a high energy, low fibre content and must be cooked. It can make up to 25% of the concentrate ration. All cereals contain more phosphorous than calcium so the ration needs to include a calcium rich feed to compensate.

Corn, soya or vegetable oil is a good source of slow release energy and is good for a fizzy horse which requires condition.

Cereals are relatively low in protein so for a horse that needs to put on condition, beans and peas are a good alternative being high in protein and energy. They can be fed crushed, split or micronised. Soya bean meal is a good source of high quality protein, being high in lysine.

Compound feeds provide a balanced ration when fed in the amount recommended for the type of work the horse is doing. If the horse is fed less then a vitamin and mineral supplement may be required. A supplement may also be required if a horse is sick or stressed.

Hay should have a greenish colour, smell sweet and be free of mould. All hay contains some dust which is a source of respiratory problems. Although soaking or steaming reduces the dust it also reduces the nutritional content.

Haylage is cut between heading and flowering, partially dried and vacuum packed. This process preserves more of the nutrients and eliminates dust. The main disadvantage of haylage is that once opened a bag must be used within a few days as it starts to deteriorate when exposed to air.

Forage is essential in the diet both to produce a slow release of energy and, as it is eaten in large volumes, to fulfil a horse’s psychological need to chew.

Concentrates often contain a high proportion of cereals which are a good source of starch and therefore provide energy. They may be fed as they are (straights) or incorporated into a prepared compound feed.

Racehorse in action. Oats are the most popular cereal for horses. They are palatable and more easily digested than other cereals Oats are usually bruised or rolled to break the husk and make them easier to digest but other cereals need to be cooked to make their starch more digestible – the main processes being micronising and extruding. Micronising uses infra-red heat to convert the moisture in the grain to steam and cook it internally. The dry extrusion method subjects the grain to intense pressure and heat. However the processing also destroys the vitamin content.

Any excess carbohydrate in the diet will be stored in the liver and muscles as glycogen or converted to fat.

Fats are very energy dense, providing an additional energy source. They are stored in the body as triglycerides which are compounds of glycerol and fatty acids. Some fatty acids can be synthesised in the body but some must be provided in the diet. Triglycerides are stored mainly as subcutaneous fat which also helps to prevent excessive heat loss.

Despite the fact that the horse’s natural diet is low in fat, horses can use fat as an energy source very effectively. Feeding fat (usually in the form of soya, corn or vegetable oil) delays the onset of fatigue and accelerates recovery. If fed over a long period it improves the body’s ability to use body fat as an energy source during exercise. This allows the horse to continue for longer before the need to use muscle and liver glycogen (which results in fatigue). Oil is therefore increasingly being fed to endurance and performance horses. It is also useful for replacing starch in the diet of fizzy horses as it provides about twice the amount of energy as the same weight of carbohydrate.

Protein is broken down during digestion into its constituent amino acids which are needed for tissue and muscle development during growth and exercise. It is not generally used as an energy source and will not make a horse fizzy.

Horses can produce certain amino acids within its body but others (known as the essential amino acids) such a lysine must be provided in the diet. A protein is described as high quality if it contains a significant amount of essential amino acids. Cereals are low quality whereas soya beans and milk are high quality.

Adult horses generally only need 8-10% of their diet to be protein but growing horses and lactating mares need more – around 16%. Any excess protein in the diet is broken down by the liver and converted to fat or excreted in the urine.

Vitamins are organic compounds required in small amounts for various functions in the body. For example vitamin A is needed by the immune system and for reproduction; E ensures optimum function of reproductive, muscular, circulatory, nervous and immune systems; H (biotin) improves hoof and hair quality and is needed for fat, protein and glucose synthesis; K helps blood clotting. Vitamins can be fat soluble (e.g. vitamin A, D, E and K) which can be stored in the liver or water soluble (e.g. vitamin C, H and B-complex) which cannot be stored and therefore need to be supplied daily

Many vitamins can be found in green, leafy forage so horses in light work on good grazing should obtain adequate amounts. Vitamin D is obtained from sunlight through the skin so horses that are stabled for most of the day or are only turned out in rugs may require a supplement. The horse naturally produces vitamin C in the kidneys (it is also available in vegetables and fruit) and the gut microbes produce vitamin K and B-complex so unless the horse is stressed it is not normally necessary to supplement these vitamins.

Minerals are chemical elements which are essential to maintain the body structure, for fluid balance in the cells, nerve conduction and muscle contraction. The main minerals are calcium, phosphorus, potassium, chloride, magnesium and sulphur. The ratio of calcium to phosphorus in the diet is important and should never be less than 1:1 (ideally 2:1). Cereals contain significantly more phosphorus than calcium so when fed need to be balanced with a feed such as alfalfa or limestone flour which is high in calcium.

Horses lose sodium, potassium and chloride through sweat and after hard work, where the horse has sweated a lot, electrolytes should be given to restore the deficiency. Sodium and chloride are also provided by a salt lick which should always be available.

In addition horses require certain minerals in very small quantities. These trace minerals include iron, copper, iodine, cobalt, manganese, zinc and selenium. They are contained in plant material provided the soil does not have a mineral deficiency. If feed in excessive amounts some trace minerals can be toxic. Youngsters need additional calcium, phosphorus, copper and zinc during their first two years.

Water is essential – 60% of a horse’s bodyweight is water and it is required throughout the body for a variety of essential functions

A horse can survive for weeks without food but it would become severely ill or even die within 2 to 3 days without water. An adequate supply of fresh water must therefore always be available. The amount required depends on what the horse eats – grass has a high water content so a grazing horse will need less water than a stabled horse eating hay. A large stabled horse would need about 8 gallons per day.

Feed ration

A horse’s natural diet consists of forage and this should form the basis of every horse’s diet. Horses in work also require concentrates to provide additional nutrients.

Forages are classified as grasses or legumes. The nutritional value of forages varies considerably depending on the management of the crop Common types of grass in horse pastureand the weather conditions during growth and harvesting. Horse pasture is typically made up of several types of grass and may also include the legume clover. Legumes are normally higher in protein, calcium and energy than grasses and alfalfa (in the form of alfalfa chaff) is the most common legume fed to horses.

Grass may be harvested as hay or haylage. Hay should be cut when the grasses are flowering, before the seed heads ripen and are lost. Most of the nutrients are in the leaf so stemmy hay has a lower feed value.

Compound feeds (also called hard feed or sweet feed) can be in the form of cubes or mixes and are available in variety of types which combine the above feeds in different proportions to provide a balanced ration for different types, age and work level of horse. The main categories are:

  • Horse and pony – a non-heating mix suitable for the leisure horse
  • Stud – a conditioning feed containing good levels of protein, vitamins and minerals (calcium in particular) suitable for breeding mares and stallions, and foals.
  • Yearling – containing calcium, phosphorous and lysine and designed to promote healthy bone and muscle growth in young horses
  • Veteran – designed to keep condition on the older horse
  • Racehorse/Competition – high in cereals and quality protein for the performance horse, also guaranteed not to contain prohibited substances.
  • Complete – a very high fibre feed which provides the forage as well as the concentrate part of the feed, suitable for horses which cannot eat hay due to old age or respiratory problems

Bulk feeds can be added to straight or compound feeds to increase the volume of the feed and prevent the horse bolting it down too quickly. They can also help to balance the ration when straights are fed. The main bulk feeds are sugar beet and chaff.

Sugar beet is a by product of the sugar industry and is a highly digestible source of energy, fibre and calcium. It is usually molassed which increases the sugar content. Some compound feeds include sugar beet but if added to the feed in pellet form it needs to be soaked before feeding. Chaff is chopped hay, straw or alfalfa to which molasses is often added.

Still unsure?

If you have any doubts about what to feed your horse or pony consult an Equine Nutritionist. Most feed companies are happy to provide free advice for an individual animal.

More information

Posted on 12 July, 2011

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