All animals need energy to live – all processes and functions in the body depend on energy.

When nutritionists talk about energy for maintenance, they basically mean the energy required by a horse to live and survive, without any growth, reproduction, milk production or work. In other words, the energy required to maintain the 'status quo'.

Where horses differ from most other domestic animals is that the mature horse is, in many instances, expected to perform. This means that energy provision becomes a little more complicated, as the type of feed you get his energy from can have as big an effect as the amount of energy provided.

Work level/

type of work

The work level of horses determines how much energy above maintenance they require. Horses in light work won’t need much more than a horse that is resting and therefore will do very well on a low calorie chaff plus a vitamin and mineral supplement or a good quality balancer.

It is once the work levels get up to medium and above that the horse will require significantly more energy. Another factor that then needs to be taken account of is the type of work it is doing.

An endurance horse has a very different energy requirement from a show jumper. They need to be able to go for hours on end at a relatively slow speed, whereas the show jumper needs high bursts of speed for short periods of time. This is where it is a good thing to have knowledge about how horses use energy and which types of feed will provide the right kind for your horse.

Fast twitch –

slow twitch

Horses will use energy instantly from a recent meal but, like all animals, will store excess energy for use when required. Most of this is in the muscles or body fat, although some comes from the liver.

Muscles store energy as glycogen, or triglycerides which are readily available when required. Horses have three different types of muscle fibres – type 1, 2A and 2B.

Type 1 fibres are slow twitch muscles, so are used for slower type work; Type 2 are fast twitch and, as it sounds, are utilised by the horse when faster work is required. The main point to be aware of is that these different muscle fibre types store and use up energy differently.

All three muscle fibre types have good levels of glycogen storage, with type 2B fibres having the highest glycogen stores but only type 1 and 2A have triglyceride stores and these muscle fibres are the ones used for most slow-medium speed work.

Triglyceride stores are slowly released and require oxygen. Glycogen stores are fast release and can be used up quickly if the horse requires it. These can be used both in the presence of oxygen and anaerobically (without oxygen) if a sprint is required.

A horse’s genetics will pre-determine the proportions of each fibre type in his muscles (a Thoroughbred, bred for speed, is likely to have a higher proportion of fast twitch muscles whereas an Arabian, bred for endurance, is likely to have a higher percentage of slow twitch fibres). Training cannot change the proportions but it can help by enlarging the fibres that are there in order to improve a horse's speed or endurance characteristics.

Energy can be supplied to the horse from three main sources – fibre, starch and oil/fat.

Fibre and

'super fibres'

The most important energy source for any horse is fibre. It keeps the horse’s gut healthy by helping to prevent complications such as ulcers and colic and it also provides the leisure horse with the majority of its energy requirements.

Alfalfa is a great source providing as much energy as your average cool mix. Super fibres, such as beet pulp and soya hulls, are widely used in horse feeds (including competition feeds) and provide highly digestible fibre.

The type of energy provided from fibre is slow release energy so it is ideal for horses that have a tendency to be fizzy or exuberant. It is also crucial for horses where stamina is required, like eventers and endurance horses.


Starch provides quick release energy especially within one-three hours of a meal and was traditionally been fed to working horses and horses that are required to perform bursts of speed.

Cereals are the largest source of starch; oats, barley, maize. Starch is eventually broken down and stored as glycogen in the muscles. It can, therefore, be seen that this type of feed is very important to performance horses as it will provide the main energy store for the horse’s fast twitch muscles.

Care must be taken when feeding cereals as the horse’s digestive system can only handle so much starch at once. Ensure that meal sizes are kept small (no more than 2kg concentrate in one meal, preferably less).

Oats have been a much maligned energy source, with an unjustifiably bad reputation. In fact, oats are the easiest cereal for the horse to digest and consequently the least 'heating'. Whole oats also provide good levels of fibre and oil, and are the only cereal that can be fed to the horse unprocessed.

Maize is the most heating, closely followed by barley. Cooking cereals does improve digestibility and so these should be fed in this form.

Fats and oils

Fat is a slow release energy source and is ideal for feeding to those with a slightly fizzy temperament to provide the energy but without the potentially explosive side effects of too many cereals.

Oil provides 2.25 times more energy than the equivalent weight of cereal, making it ideal for increasing the nutrient density of the diet. In other words, a lot of energy can be provided in a small amount for fussy eaters, poor doers or hard working horses.

The use of oils in feeds for performance horses also has other benefits. One is the fact that there is a glycogen-sparing effect when high oil diets are used. This basically means that the fat stores (triglycerides) are used up when the animal is performing aerobically at slower speeds, using his slow twitch muscles, and the glycogen stores are reserved/spared for the fast anaerobic sprint work.

This leads to more fuel left in the tank for when it is really required. It must be remembered that when high levels of oil are fed, extra vitamin E should also be fed (100 IU of vitamin E per 100ml of oil fed).