Horse nutrition is simple | Haygain USA
Horse nutrition is simple

Horse nutrition is simple

Exercise Physiologist Dr. David Marlin explains some useful principles of equine nutrition.

I think horse nutrition is often over-complicated! Sometimes this occurs because someone has an ulterior motive – perhaps to sell you a product or a service.

In many cases its because the author doesn’t have a good enough grasp of the subject to be able to explain it clearly. I was always taught that if you understand something thoroughly then you should be able to explain it to a 6 year old child!

Nutrition is really quite simple. You and your horse require a certain amount of water, energy, and protein on a daily basis, and vitamins and minerals over a longer period of time.

By this I mean that it is ok to miss a few days or weeks when it comes to vitamins and minerals. For most people, we actually manage to survive for 70-80 years and most of us don’t live everyday calculating the exact intake of every single nutrient. And how could we?  The composition of individual food stuffs that we eat is very complex.

If we look at the figure below which shows the nutritional breakdown for 100g of cooked brown rice we can see how complex a “simple” single foodstuff such as rice is. For example, the protein can be further broken down into its amino acid composition, the fats and oils into their components (fatty acids), etc.

Of course, those with food allergies or intolerances may take more notice of such detailed information.  And people with particular diseases or health issues may be given carefully formulated diets developed by nutritionists who do use this detailed information. But the point here is that most of us survive a very long time and are reasonably healthy because eating is something we all do in a fairly simple and relaxed, natural way. We do not need a degree in nutrition to be able to eat.


There are however some clear rules when it comes to nutrition. Consume more energy than you use up and you will put on weight. Don’t eat enough of certain vitamins and you are likely to develop health issues. Eat too little fibre and you are at increased risk of developing gastro-intestinal disease.

There are of course some groups where nutrition is more controlled. We have mentioned already people with particular health problems. Another group where nutrition is of course very important is human athletes or sports people and in many sports good nutrition plays an important part in management and training of athletes not to mention in achieving best possible performances. 

Perhaps the key message here is that our gastro-intestinal tract (mouth, oesophagus, stomach and small and large intestines) is actually quite tolerant and adaptable. We can eat a variety of foods and our GI tract manages (usually) to cope with what we give it and manages to work out what to keep and what to get rid of, with a few exceptions, such as energy!

It seems that today horse nutrition is very complicated and confusing for many horse owners. Colic, tying-up, laminitis and obesity all seem to be very common and the role of nutrition seems to be a major focus.  If many of these problems are caused by how we manage and particularly how we feed horses then they should surely be easy to solve?

Let’s start by looking at how wild horses manage their own nutrition. In the wild horses will primarily eat grasses and herbs and shrubs. They may occasionally eat fruits when these are available but they rarely eat large amounts of cereals. Depending on their habitat they may become relatively fat in Summer and thin through the Winter, reflecting the amount of food available. Even in Summer wild horses do not exclusively graze rich cultivated single grass species. Wild horses may typically cover 15km a day, but this is undertaken almost entirely at walk.

Domesticated horses live very differently. They eat what they are given. This is often single species highly digestible forage (pasture or hay). They have limited if any ability to select different food sources. They may be given concentrated feeds. They are wormed and vaccinated which can influence GI function. They appear to be at increased risk of developing nutrition related health problems.

However, it’s essential to recognise that the domesticated horse is usually required to work harder and differently to the wild horse. Domesticated horses in light-medium training may also cover 15km a day but this is likely to be a trot, canter and gallop as opposed to at walk.  This requires a greater intake of energy than walking the same distance and is why many horses require supplemental energy to that provided by forages alone.  With domesticated horses it is more likely that we are also trying to maintain a “normal” body condition all year around.  We don’t want to be competing fat horses in the Summer months when the competitions are happening.  We also often use wormers, antibiotics and vaccines which on balance have a beneficial effect in ensuring better health and welfare but these can also influence GI function.  But perhaps the most important point is that domesticated horses will live longer and probably suffer less than horses in the wild.

So to feed a horse that is not required to do anything other than be a “lawnmower” to keep it alive should be fairly straightforward. However, many populations of horses do have requirements above that of just pasture or hay. Mares in foal, growing horses, horses with specific health problems (e.g. horses with skin disease, horses with respiratory disease, horses with poor digestive function, horses in training and competing,older horses, etc.

So we come to the principle that there are different qualities of nutrition for horses. There is adequate nutrition, there is poor nutrition, there is good nutrition and then the pinnacle is optimal nutrition. With optimal nutrition we are looking at a detailed analysis of the horses’ diet and that individual horses specific requirements. We may adjust the diet based on observation of how the horse responds and measurement. With expert input and with specific and appropriate tests this approach is aimed at ensuring that nothing from a nutrition perspective is limiting the horse.  Of course, this usually has a cost in respect of dietary feed analysis, blood tests, urine tests, faecal tests.

At the other end poor nutrition is easy to understand and recognise. Feeding low nutritional quality, mouldy hay and no electrolytes to a horse in hard work is unlikely to allow that horse to perform at it’s optimum.

So in practice, for most horse owners we should aim for good nutrition. So what are some simple and key rules for feeding horses?

  • Forage must form the basis for any diet for any horse. Forage (pasture or hay or haylage) does not have to be highly nutritious but should be of good hygienic quality (low moulds). Too low forage intake leads to increased risk of colic, gastric ulcers and behavioural problems.
  • For horses in any form of work it is likely that some additional energy will need to be provided in the form of hard/concentrate feed. Cereals and grains (source of starch) are not a problem if used correctly and become increasingly important the harder the horse is working. The most common problems are:
    1. Feeding too much – so the horse becomes fat
    2. Not splitting between enough feeds – should be split between at least 3 feeds a day
    3. Introducing too quickly
    4. Giving extra before competing
    5. Not giving with hay
  • Fat/Oil energy is excellent for coat and skin, for horses with GI problems, for horses that struggle to maintain weight, have a poor appetite and are prone to tying-up. However, high fibre, low starch, high fat/oil diets for horses in moderate to hard work have a negative effect on performance.
  • Control body condition. Thin horses are much happier and healthier than fat horses.
  • Provide electrolytes. ALL horse diets are marginal or deficient in sodium. Forages are high in potassium. ALL horses should receive some supplemental salt (e.g. 25g per day of ordinary salt). This becomes increasingly important or horses in more than light work. For horses in more than light work a balanced electrolyte should be fed on a DAILY basis, not just before and after a competition or hard training session. Poor performance due to electrolyte imbalance is VERY common in horses.
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