Feeding horses – the basics

A basic understanding of the horse’s digestion is necessary in order to understand how to feed a horse according to its needs. Most (riding) horses are often overfed with the amount of feed and consequently the energy supplied. Diet-related diseases are the result. The requirements for feeding horses do not only differ from breed to breed, but also depend on how they are kept, their age, state of health, size and use.

Three blue food buckets with contents

Despite different feeding requirements, all horses have the same sensitive digestive system. What makes the horse’s digestion so unique and what you as a horse owner need to know about it in order to avoid diet-related diseases is explained in this guide.

The horse’s digestive system – a sensitive system kept alive by bacteria

Mouth cavity

The feed is taken in by the horse with the help of the lips, the tongue and now and then also with the incisors. Horses are essentially gourmets: their oral cavity has up to 35,000 taste buds.

By comparison, humans have just 10,000, so it is possible for the horse to sort out even individual crumbs from the mixes that it does not like.

A horse eating grass

In the mouth, the feed is crushed between the cheek teeth, then well salivated. Salivation is very important for the gliding ability of the crushed feed and further digestion. However, there are no starch-breaking enzymes in the saliva, therefore pre-digestion only takes place in the oral cavity by crushing the feed. As a result, the horse needs a lot of rest and time when eating. A large horse needs between 40 and 50 minutes for one kilo of roughage, and about 10 minutes to break down one kilo of hard feed. If the horse does not have the time or is under stress, it will start to gorge. As a result, hard feed can then collect unchewed at the entrance to the stomach and lead to a blockage of the pharynx.

Our tip:

If the horse tends to gulp its hard feed, place large, rounded stones in the trough. These make the horse eat more slowly.

But be careful: do not use pieces of salt lick for this. You can find out why here.

Stomach

The horse has a relatively small stomach in relation to its body size. A horse’s stomach can hold between 7 and 10 litres and can even expand to twice that size. However, this is a great strain on the organ, and over-expansion leads to colic symptoms. To prevent this, you should know the following:

If the horse has had enough time and rest while eating, the mash arrives in the stomach well chopped up and soaked – it can pass through the stomach quickly.

However, if the feed has not been sufficiently chewed and salivated, it is more difficult for the gastric fluids to break down the half-chewed feed. The feed stays in the stomach longer and the stomach wall overstretches.

It is especially critical if the hard feed is given before the hay. The hard feed then lies heavy and long in the stomach. If the hay with a lot of water (saliva) is given on top, the stomach is overfilled faster and causes abdominal pain – the horse has colic. It is therefore advisable to give the hay at least 30 minutes before the hard feed, so that the horse is already satiated and does not swallow the hard feed unchewed.

Small intestine

The horse’s small intestine is 20 metres long, but has an even larger surface area due to villi (finger-shaped elevations of the small intestinal mucosa). In the small intestine, proteins, fats and easily soluble carbohydrates are broken down into their components. For this purpose, bile is injected into the intestinal contents from the liver. Since the horse does not have a gall bladder that produces fluid in stock, the liver constantly releases the secretion.

Because of the low enzymatic activity, the horse’s ability to digest starch is greatly reduced. It is therefore important that the horse is fed little and only easily digestible starch, such as that found in oats. Feeds with a high and hard-to-digest starch content (e.g. maize) should be hydrothermally digested, i.e. the grains are softened under heat and moisture and thus become more digestible for the horse.

Starch that has not been digested in the small intestine moves on to the large intestine, where it destroys the balance of the intestinal flora. The microbes found there, which are essential for the horse’s survival, are killed off by the lowering of the pH value and fermentation processes. Therefore, good precaecal (before the large intestine) starch digestibility should be considered when choosing feed.

Primary location of horse digestion: the large intestine

With around 20 kilograms of bacteria, the horse carries a whole host of digestive aids in its large intestine, which are essential for the horse’s survival. The bacteria want to be well nourished, otherwise the intestinal flora will be unbalanced. In 33 to 44 hours, the microorganisms break down the feed pulp and the poorly soluble plant-based structural substances cellulose, hemicellulose and pectins. In doing so, they release volatile fatty acids, B vitamins and trace elements, which the colon wall absorbs. The feed supplied determines the orientation of the bacteria. After acclimatisation, they adapt to the feed and multiply accordingly. Therefore, feed changes should always be treated with caution, as they – if carried out too abruptly – can harm the bacteria. In addition, unsuitable feeds, such as silage, can disturb the intestinal balance. Due to fermentation, there are no longer any hard-to-digest, vegetable components in the feed on which the microbes could feed, whereupon they die.

The further the feed mush travels in the large intestine, the more water is extracted from it. Towards the end, bulges in the wall of the large intestine give the faeces their typical ball shape before they are excreted.

The 10 basic rules of horse feeding

1. Hay has priority

For the former steppe animal, roughage in the form of high-quality hay has priority in feeding. The high dry matter content (approx. 88 %) and crude fibre content form the nutritional basis for the intestinal bacteria. Therefore, the horse should have 1.5 kilograms of hay per 100 kilograms of body weight per day. For a warmblood weighing 600 kilograms, this means at least 9 kilograms of hay. Horses not kept on straw should receive at least 2 kilograms of hay per 100 kilograms of body weight to avoid long fasting.

To avoid colic, the horse should be given the hay at least 30 minutes before the hard feed.

2. Prolonged eating time without long periods of fasting and small amounts of feed

Horse at the hay net

The horse’s stomach continuously produces stomach acid. To prevent the stomach wall from being damaged by the corrosive acid and stomach ulcers from developing, the stomach should constantly have feed to decompose. Fasting should not be longer than four hours.

Due to the small stomach volume of 7 to 10 litres, the horse should be given many small portions throughout the day. With one scoop of oats (about 1 to 1.5 kilograms) plus saliva (about 3 litres), the stomach is already half full. To avoid an overfilled stomach, the total amount must be divided into several, small portions. Three or more portions spread over the day is optimal.

To prolong the feeding time and to avoid hectic eating, haynets are suitable. For hard feed, large, round stones can be placed in the trough.

3. Moderation in protein feeding

Protein is an important source of essential amino acids, which are crucial for muscle and cell development. However, the protein intake should be adapted to the intensity of work and the requirements. The horse’s digestive system can tolerate an oversupply of protein up to two to three times the required amount. However, a permanent over-supply damages the detoxification organs, namely liver and kidneys, and eventually leads to metabolic diseases. The majority of leisure horses/happy hackers do no more than light work and cover their protein needs sufficiently with hay.

Did you know?

Studies have shown that laminitis is not caused by an excess of protein, but by an excess of fructans and starch. A constant overload of the multisugar fructan, which is formed in grass, leads to a imbalance of the intestinal flora in the large intestine, whereupon the microbes die off. The toxins released enter the bloodstream and the entire organism becomes over-acidic and the laminar corium inflamed.

4. Beware of too much starch in horse feed

The horse digests starch mainly in the small intestine. Undigested starch that enters the large intestine upsets the balance of the intestinal bacteria. As a result, the intestinal bacteria die and release endotoxins (toxins) that enter the bloodstream. Likewise, fermentation and consequent flatulence, tension and irritation of the mucous membranes can occur. With an inflamed intestinal mucosa, the ability to absorb nutrients, minerals and trace elements is reduced. Therefore, feed with easily digestible starch should be used in horse feeding. Oats are suitable as hard feed because they contain less starch than other types of feed and are easily digestible. If you want to feed the horse large amounts of oats, the amount should be divided into at least three portions throughout the day.

Starch content of individual feed:

1 kilogram of oats contains around 390g of starch

1 kilogram of maize contains around 650g of starch

1 kilogram of hay contains around 18g of starch

Ideally, a horse should get a maximum of 1g of starch per kg of body weight per meal. This means that a horse weighing 500 kilograms may receive a maximum of 1.3 kilograms of oats per meal.

5. Basic mineral supplement is compulsory

To maintain various bodily functions, the horse needs bulk and trace elements. The bulk elements include calcium, potassium, magnesium, sodium, phosphorus, chlorine and sulphur. For the horse, a balanced calcium:phosphorus ratio (Ca:P) of 1 to 3:1 is particularly crucial. Both elements account for up to 70% of the horse’s mineral content and are mainly stored in the bones. A shifted Ca:P ratio can lead to demineralisation of the bones, ultimately resulting in pain, fractures and osteoporosis. As a rule, the calcium-phosphorus requirement is covered with 1.5 kg roughage per 100kg horse weight. However, if the amount of roughage is below the recommended values, the deficit should be compensated by a vits and mins supplement with a balanced Ca:P ratio.

Trace elements include zinc, iron, copper, manganese, iodine, selenium and cobalt. However, intensive land cultivation has washed out the soils, so that zinc, selenium and copper in particular are often in short supply in hay and grass. The nutrient deficiency should be compensated by a good basic vitamin and mineral supplement.

6. Moderation in oil feeding

Fat in the form of oil is an important source of energy, which is particularly important for horses in competition sports or for horses fed grain-free. With just 50 milliliters of oil, the horse receives 2 megajoules (MJ) of energy. However, very few leisure horses need such high, additional energy values, which is why most horses should not be fed with oil.

Excessive fat intake can hinder gastric emptying and also reduce microbial activity in the large intestine. Therefore, the horse should not be fed more than 1 to 1.5g of oil per kg of body weight per day. These servings should be given throughout the day.

Oils that are well tolerated by the horse are soy, sunflower, rapeseed, linseed and milk thistle oil.

Feed oils

7. Establish a fixed feeding time

Horses are routine animals with an internal clock. In order to avoid stress before and during feeding, fixed feeding times and a precise order of feeding are recommended. Automatic feeders are the optimal solution for the administration of hard feed. In this way, food aggression, bolting, kicking walls and biting into bars are prevented.

8. Gradual change of feed

The horse’s digestive system is highly sensitive and easily upset. Abrupt changes in feed massively disturb the environment of the intestinal bacteria. These bacteria need a period of time to get used to new feed compositions in order to be able to adapt to them and reproduce accordingly. Plan at least two weeks for the feed changeover, during which you replace small portions of the old feed with the new one every day.

When changing the feed, the analytical components are important, not the type of feed itself. If, for example, the former mix and the new cubes have the same analytical components, the horse can be changed over without a gentle transition.

You should be particularly careful when changing from winter feed (exclusively hay) to summer feed (pasture grass) – and vice versa. In summer, there are hardly any intestinal bacteria left that can break down the hard-to-digest, vegetable components of the hay. These must first be formed again, which is why hay should be fed parallel to the pasture grass towards the end of the grazing season. In the same way, hay should be fed at the beginning of the grazing season.

9. Provide sufficient fresh drinking water

Horse drinks from the water tub

Water is crucial for a balanced digestive system, functioning thermoregulation and a balanced metabolism of the horse.

A horse has a drinking water requirement of 5 to 13 litres per 100kg body weight. This means that a 600-kilogram warmblood can drink between 30 and 80 litres a day.

The amount of water depends on the outside temperature and the intensity of work. Make sure that the horse has free access to clean, odourless water of drinking-quality at all times.

10. Salt lick at free disposal

A horse that sweats due to work or high outdoor temperatures loses important electrolytes through sweat. For every litre of sweat, the horse can lose about 8.5g of sodium chloride. This electrolyte loss can be compensated for with a salt lick.

Do not place the lick in the feed trough, but hang it up or place it in a lick holder to keep it clean. If the salt lick is in the feed trough, the horse is forced to ingest salt in excess of its needs, which is not beneficial to its health.

Horse licks

Inexperienced suckling foals should be denied free access to salt so that they do not get diarrhoea.

Horses that literally bite the salt off in chunks when they are adults had unrestricted access to salt when they were foals. The salt lick should be taken away from these horses and only presented when the horse has sweated.

The 10 basic rules summarised:

Handout about the 10 basic rules of feeding horses

What types of feed are there?

Feed can be broken down from the varieties into its components and ingredients. An understanding of the different types of horse feed will make it easier to calculate the feed plan according to needs.

Handout on types of horse feed

How much feed does my horse need? The 1×1 of ration design

For a fleeing animal such as the horse, being overweight or underweight can be life-threatening in the wild. Although our horses no longer have to flee from predators, their entire musculoskeletal system and their metabolism are adjusted to an ideal weight. In order to maintain or achieve this, a feed plan optimally adapted to the movement requirements is indispensable.

Each horse has to be considered individually. Even with horses within a breed, the way of keeping, work, age, health and physical condition must always be assessed independently.

What are the most important factors in the feed plan calculation?

  1. The basis of every feed plan calculation is the horse’s body weight: the most accurate result is provided by a horse scale. If you don’t have one, you can determine the weight by measuring the horse with a simple formula:
    Chest circumference (cm)² x body length (cm) / 11900.
    The result is accurate to +/- 20 kilograms.
  2. Visual assessment of the horse: Always keep an eye on the horse and its physical condition and adjust the feeding if necessary. Even if the feed plan is precisely tailored to the horse, the metabolism can thwart the whole idea. Illnesses, injuries or the change of coat also play a major role. So always keep an eye on the horse and its physical condition and adjust the feeding if necessary.
  3. Body Score Index: As a guideline for the visual assessment of the horse, the Body Score Index can provide information about muscles and visible fat reserves. It ranges from 1 undernourished to 5 optimal to 9 extremely fat. The optimum varies from breed to breed. The optimal BSI of an Arabian horse tends to be 4, whereas the normal range for a Fjord horse is 6. The fatness of the neck, withers, spine, flanks, inner thighs, tail set, shoulder, ribs and the transition from shoulder to neck is assessed.
  4. Identify the horses’s energy requirements: A distinction is made between maintenance requirements and performance requirements. The energy the horse needs to maintain its body functions and temperature is called maintenance requirement (digestible energy DE in MJ).
    In addition to given guideline values, you can also use the following formula:
    0.6 MJ DE x body weight0.75
    The performance requirement (DE in MJ) is the additional energy that exceeds the maintenance requirement and is necessary to achieve a performance. This can be for training, growth, lactation or breeding. In terms of performance requirements, a distinction is made between light work, moderate and hard work. Most leisure horses/happy hackers perform light work, whereby 25% more energy should be supplied to the maintenance requirement. A show horse does moderate work – the energy requirement increases by 25 to 50%. Only a few horses do hard work, such as racing, eventing and endurance sports. In this case, the horse should be supplied with up to 80 % more energy in addition to the maintenance requirement.
    You can also calculate the total energy requirement with the following formula:
    0.6 MJ DE x body weight0.75x 1.25
    0.6 MJ DE x body weight0.75x 1.25 to 1.5
    0.6 MJ DE x body weight0.75x 1.5 to 1.8
  5. As the energy requirement increases, so does the requirement for digestible crude protein (DCP): Proteins are essential building blocks of the body and take over important functions in the metabolism. The need for protein increases proportionally to the size of the horse – large, heavy horses need more protein than small, light ponies. The need also increases with the intensity of the activity to be performed. However, the amount of protein supplied should be checked with a critical eye at all times. Too much can put an excessive strain on the metabolism.
    However, it should be noted: A protein deficiency does not usually occur if the energy requirement is covered by the feed.

How do I correctly manage my horse’s feed plan?

First, the maintenance requirement, i.e. the horse’s basic energy supply, is calculated. Knowledge of

  • The weight and size of the horse
  • Age
  • Breed or type of horse (heavy horse, warmblood, thoroughbred, pony)
  • Size
  • Health condition (diseases can increase the need for energy and nutrients)
  • Grazing and roughage
  • Turnout opportunities
Horse and pony

The following guideline values for energy and nutrient requirements result for the metabolic maintenance:

BM in kgDE in MJDCP in gCa in gP in gNa in gK in gMg in g
100199553252
200321601064104
4005427020128208
500643202515102510
600736353018123012

For example: A 600 kilogram horse needs 73 MJ of energy for maintenance. In summer, it is put out to pasture for 6 hours and is kept in a stable overnight. In the field, it eats approx. 4 kg per hour, i.e. a total of 24 kg of pasture grass (1 kg of pasture grass = 2.3 MJ DE). Through grazing, the horse achieves an energy value of about 55 MJ. In order to reach the energy requirement for maintenance, the horse receives about 3 kg of hay with an energy value of 7.3 MJ/kg before and after grazing. Thus, the horse, which is not ridden or worked, is sufficiently supplied with 6 h of grazing and 3 kg of hay.

As a second step, the horse’s performance is calculated. There are also guidelines for the extent to which light, moderate and hard work are defined:

Handout on horse feeding and the energy requirements of the horse

For example: Our 600 kilogram leisure horse/happy hacker is in light work in the summer. A quiet ride for an hour, now and then cantering. Therefore, 25% more energy must be added to the maintenance requirement. The total energy requirement is now 91.25 MJ DE.

With 6 hours of grazing we have already covered 55.2 MJ. A total of 36.05 MJ is still missing, which has to be covered by roughage and/or hard feed. There are the following possibilities:

  • 5 kg hay (7.3 MJ per kg) = 36.5 MJ EN
  • 3 kg hay (7,3 MJ per kg) + 1.2kg oats (11 MJ per kg) = 36,06
  • etc.
Example for feed plans