Feeding Fats to Horses

Feeding Fats to Horses
Renee Swanepoel N Dip Equine Studies, SANEF Level 1

I was first introduced to the idea of feeding fats to horses a couple of years ago by a friend of mine whose horse looked like something that had stepped out of a showing manual. She was turned out to veld all day long and brought in at night. I was so disappointed to find the same horse feed in her store as I had in mine. Only upon further investigation I discovered that she was feeding her mare a cup of oil every night with the evening feed. Armed with my new-found secret, I immediately ran out to buy a bottle of Black Cat Sunflower Oil, and I have never looked back.

Fats and oils seem to have become taboo in this very health-conscious society we live in. The thought of feeding fat (or oils) to their horses will drive some owners to near hysteria. Thoughts of blocked arteries, heart attacks, and overactive, nutty horses is what goes through many people’s minds when they imagine giving oils to their horses.

Research on the feeding of fats and oils has been slow in past years, but there is now more and more interest in the subject, and more research is being done with great findings. More research has been done regarding the use of oils and their effects on the equine body, and research is currently focusing on the importance of Omega-6 and Omega-3 fatty acids. This will give us even more insight into the potential uses of a fat supplement to the equine diet.

Fat is basically structured as follows:

The Triglyceride molecule looks almost like an “E” – the backbone of the “E” is a molecule of Glycerol which can be converted to a sugar (glucose) if the arms are separated. The arms of the “E” consist of long chains of Carbon atoms and they are called ‘Fatty Acids’. The shorter the fatty acid chain, the more likely that the fat is a liquid at room temperature, and those are commonly referred to as ‘oils’.


The horse’s digestive system is actually very well adapted to the utilization of fats and oils. In humans, bile is excreted to help break down and digest fats, and is stored in the gall bladder. The horse also excretes bile, but it does not have a gall bladder, so bile is continuously excreted into the small intestine, where it can work on fats. This means that fats and oils that are added to the diet are actually 80% - 90% digestible. With a typical grain and hay diet, the horse is only able to utilize about 50% - 60 % of the energy provided by those feedstuffs.

People are often worried about the effects of feeding a higher fat diet to their horses because they are very aware of the dangers of a high fat diet in humans. A high fat diet in humans is defined as a diet containing over 30% of calories from fat. A typical high fat diet in the horse contains about 10% of calories from fat. Studies have not been conducted over a long term to assess the effects of a high fat diet in the horse, (the longest study to date was done by the Kentucky Equine Research Centre in Australia, and lasted 18 months) but current evidence would suggest that there are very few, if any, ill effects related to feeding oils.

Benefits of Feeding Fats and Oils:

1. Source of Concentrated Energy

One of the great characteristics of oils and fats is that it is very energy dense. This means that a given quantity of vegetable oil has about 3 times the caloric value of the same amount of oats, and approximately 2,5 times more calories than maize. (Corn) A horse’s digestive system can only handle a certain volume of food per day. Introducing oils to the diet means that you can increase the number of calories being taken in, without increasing the volume of the ration beyond what the horse can handle.

Oils are very useful when dealing with animals that have a higher caloric requirement, or are unable to ingest large quantities of food. Lactating mares, underweight animals and older animals respond very well to this type of supplementation. Older horses very often have poor teeth and cannot chew their food properly. Supplementing with fats and oils means that the caloric intake can be maintained without having to feed large amounts of food. Horses that are ill can also have their concentrates cut while maintaining the calories with oils.

2. Source of Essential Fatty Acids

Essential fatty acids have come under the spotlight recently with regards to their effects in humans, and there are definitely more studies that need to be done regarding the positive effects in horses. The horse is able to make its own fatty acids, but will never be able to make as much as he requires, so the rest of the requirement is filled by his diet. The essential fatty acids that are of most importance are linoleic acid (Omega 6) and alpha-linoleic acid (Omega-3).

Various oils contain different ratios of Omega 6: Omega 3 fatty acids. Omega 3 fatty acids have recently come under the spotlight in human nutrition, as they have been found to be useful in the prevention and/or treatment of heart disease, thrombosis, hypertension, renal disease, arthritis, inflammatory disorders and possibly even cancer. More research needs to be done regarding its possible effects in horses. The fatty acids have a profound effect on the coat and skin, as well as an improvement in the condition of the hooves. After 3 to 5 weeks after commencing with oil supplementation, the coat will appear shiny, sleek and beautiful. Horses with dry, itchy skin are also often improved when supplementing oil.


3. Assists in Absorption of Fat-Soluble Vitamins

Vitamins A, D, E and K are absorbed in the body with fat, so the addition of fat to the diet will assist in that absorption. The horse is able to make its own Vitamin D from exposure to the sun, and Vitamin K can also be made by the microbes in the hindgut. (Microbes are very important in the fermentation process and fiber digestion in the hindgut.) Supplementation with oil will have a positive effect on the absorption of these vitamins.

4. Benefits Athletic Performance

The benefits to athletic performance are muti-factoral, and include the following:
- Reduction in thermal load
The process of fermentation, which the horse uses to digest his feed produces heat as a by-product. The most heat is produced by the digestion of fiber, then protein, starch and then lastly, fats and oils. The total body heat production is reduced by about 14% when the horse is fed a high fat diet. This means that less energy is lost as heat, and more is available for exercise. Horses are also able to handle hot, humid weather better, and fat supplementation has become a major part of the management of horses competing in hot weather, such as the Atlanta Olympics. Because horses sweat less, they also lose less electrolytes and water.
- Greater muscle glycogen utilization and delayed fatigue
The horse has two sources of energy to call upon when exercising – glucose and fatty acids. Glucose is stored in the body as glycogen in the muscle and liver. Fatty acids are stored in body fat and around muscles. The longer the duration of the exercise and the more fit the horse, the more he will use stored fat as energy to fuel the workout. Some glucose is always needed during exercise, but the reserves in the muscle and liver are often quite limited. The onset of fatigue is sped up when these reserves are used up. When the horse is fed a high fat diet, his body learns to use the fatty acids as fuel during exercise and the onset of fatigue is delayed.

Horses fed on a 10% added fat diet were able to trot for 35 minutes before their heart rates reached 160 beats per minute. This heart rate was reached in 20 minutes by the group not being supplemented with fats.

It takes about 11 weeks for the horse to adapt to the change in glucose utilization.



5. Minimises Digestive Upsets

Horses evolved to take in a large amount of fiber, and very little starch. Some people would say that the horse’s digestive tract was very poorly designed! When the horse is asked to perform at higher levels, starches have traditionally been added to the diet to compensate for the increased caloric requirements. The problem arises when high amounts of starch are added to the diet – the more grain fed, the more starches pass through to the hindgut, where they can disrupt the normal levels of microbes present. The higher levels of starch in the hindgut change the pH, and as a result the microbes that are responsible for digestion cannot survive. This causes many different problems, like diarrhea, colic, laminitis, etc.

Studies have shown that up to 10% of the starch (concentrate) portion of the diet can be substituted for oil. This means the horse is able to consume less hard feed but maintain the same condition. Less concentrates can lessen the chances of digestive upsets.

A study has shown that up to 16% of racing horses on high grain diets have a faecal pH level below 6,4 and show symptoms of low grade laminitis – with foot soreness, reduced stride and less than optimum performance. The race times of 14 out of 15 TB’s racing over 1600m was improved after consuming a diet containing 12% of its energy from oils, as opposed to a grain diet with only 2% energy from fat.


6. Favorable Effect on Temperament

After being fed a large amount of carbohydrates, the blood glucose levels rise and insulin is secreted to bring the blood glucose levels down to normal levels. The insulin also has an effect on the metabolism of thyroid hormones. This has an effect on the horse very similar to a ‘sugar high’ in humans. Horsemen talk about ‘fizzy’, excitable horses, and are referring to this effect that starch has on the behaviour of the horse. With a high fat diet, the rise in blood glucose levels is lower, thus the effect on behaviour is less. Horses appear much calmer and energy levels are more constant, not the ups and downs that is seen with high starch diets.

7. Benefits Horses with Recurring Tying Up

Tying up, or Azoturia, is a muscle condition that causes cramping and muscle damage commonly to the muscles of the gluteal and lumbar region. It varies in severity – from poor performance to severe pain with sweating, cramping and immobility. The exact cause of the disease is not exactly understood, but there are various factors that have been identified as triggers. Traditionally, the disease was seen in the draught horse in work that was rested or the weekend on full feed, and returned to work. (Hence the name Monday Morning Disease) It is thought that muscle glycogen accumulates during the rest period and when used during exercise it produces excessive lactic acid. This causes local tissue damage and constriction of the blood vessels, resulting in decreased blood flow to the tissues and further reduction in lactic acid removal. Other predisposing factors include: Thiamine and vitamin deficiencies, hormonal influences, electrolyte imbalances and viral causes.

Using oil in the diet reduces the amounts of starch being fed, and thus reduces the extra glucose used for the synthesis of glycogen in muscle.



Introducing fats and oils to the horse’s diet is a relatively easy process and the following guidelines should be taken into account:

- Type of Oil

When deciding on the type of fat to supplement with, the decision will be influenced by the palatability and availability of the oil. It is no good spending thousands of Rands on a product that your horse will not eat. Fish Oils have been shown to be the best oil supplements, but most horses will not eat it. Corn oil is a very popular fat supplement, although there is research that shows that it is rather low in Omega 3 fatty acids, and very high in Omega 6 fatty acids. Linseed also has a high fat content, but it must be boiled thoroughly before use, as raw linseed contains cyanide.

I would recommend the following fat supplements for use in the horse:

1. OILS:
Corn Oil
Sunflower Oil
Canola Oil
Flax Oil
Soybean Oil
Peanut Oil

There is great debate whether corn oil or sunflower oil is better for the horse. I have been using both, and have found no difference in the effect on the horse. Sunflower oil can be cheaper and more readily available than corn oil, but it very much depends on owner preference. Sunflower oil is slightly higher in Omega 6 fatty acids, but this difference is so small that I do not feel it has any bearing when deciding which oil to feed. Corn oil has been found to be more palatable than sunflower oil, but I have yet to find a horse that turned his nose up at sunflower oil. If it is introduced slowly, there is no reason why he will not take to it.

2. OTHER:
Boiled Linseed
Rice Bran*
Flaxseed*
Full Fat Soya meal
Sunflower Seeds

Commercial Horse Feed with added oil content (ask your feed merchant – they are not very common in SA, but I do know of one or two)

* Rice Bran contains approximately 22% fat, and Flaxseed about 40%. It must therefore be remembered that a much larger amount of these products must be fed to achieve the same results as feeding oils, which are 100% fat. Another problem with feeding Bran is the high phosphorous content, which presents a whole new set of health problems. If you are feeding any type of bran regularly, you should be supplementing the diet with calcium to correct the imbalance.


- Amount Fed

Adding an amount of oil to every feed is the easiest way to supplement the diet with extra fat. Generally speaking, add 100g of oil per 100kg bodyweight per day. (That means, a 500kg horse will be able to tolerate two cups of oil per day) If you are feeding more than that recommended amount, you should also be giving a multivitamin containing Vit E, as a very high fat diet requires more anti-oxidants. A balanced, high fat commercial feed will have the additional vitamins added already, so you need not worry about supplementing it.

For oils to work effectively in the body, they need to be taken in with some carbohydrates, thus it is unwise to cut down on all starches and feed only oils!

Like all feed changes, oils should be added very slowly to the diet, to give the digestive system a chance to adapt. The daily amount should also be split into two to three smaller feedings. If you are feeding oils, add approximately 50ml extra every second day for ten days (or until you reach your recommended amount) to give your horse a chance to adapt to the changes.

If oil is added slowly to the ration, most horses will take to it well. If your horse is very fussy and will not eat it, experiment with different types of oil until you find something that he will eat. It is normal for the stool to become loose for a few days whilst adapting to the diet, but this should clear up.

It will take approximately 3 to 4 weeks for the body to adapt to the oils and for you to begin to see results. You will notice the change in coat condition quickly – after 2 weeks. For the body to adapt to using fats to enhance athletic performance takes 2 to 3 months, so it is best to start your horse off as early as possible – especially if you are doing endurance riding.

Also remember that once you are supplementing with oils, you may have to cut down on your concentrate feed to prevent obesity! Keep a watchful eye on your horse, and if you notice him / her putting on weight, cut your concentrates by up to 10%.

- Storage of Oils

Oils need to be stored correctly to prevent rancidity. Rancidity is caused by the decomposition of fats and other lipids by hydrolysis and/or oxidation. The harm caused by rancid oils are brought about by the destruction of vitamins E, F, and A, both in the oil itself and in the horse’s body. Anti-Oxidants (like Vit E) are often added to oils to slow down this process. Horses will generally speaking not eat rancid fats.

It is thus very important to store oils in a cool, dark place. Try to purchase oils that are in solid coloured containers and do not keep stock for longer than a few weeks. Keep bottles tightly closed, and add oils to the feed right before feeding the horse – do not let your bucket of oil and concentrate feed stand in the sun for ages before offering it to your horse. Well stored vegetable oil can be kept for two months.


In conclusion, I would like to encourage all horse owners to try supplementation with oils. You will be amazed at the glossy coat, weight gain and improved performance of your best friend!