Omega 3 Fatty Acids

Omega 3 fatty acids have made the headlines numerous times over the past year. Often touted for their many health benefits to humans, they are also appear to be beneficial to your horse.

The most common omega-3 in the equine diet is alpha-linolenic acid.

Omega-3's, like omega-6's, have numerous important functions throughout the body. They

  • are an essential component of many body structures
  • play an important role in immune function
  • are an important part of the phospholipid bilayer of cell membranes
  • play an important role in vision

They can also be metabolized to make a hormone-like substance called an eicosanoid (more on those later!).

It is suggested that 10:1 is the optimal ratio of omega-6:omega 3 fatty acids for equine diets.

Sources of Omega-3 fatty acids

There is only one naturally occurring source of omega 3 fatty acids in the equine diet: fresh grass.

However, flax seed which is commonly supplemented to horses, is also very high in omega-3's. 53% of the fatty acids found in flax seed are alpha-linolenic acid.

However, there are other sources of omega 3 fatty acids in the equine diet...these other sources just do not contain as much omega-3 as fresh grass and flax seed.

11% of the fatty acids in canola oil are alpha-linolenic acid. Soybean oil comes in at 6% alpha-linolenic acid.


Eicosanoids are chemicals that regulate vital body functions, such as blood pressure, blood clotting, immune response, and inflammation response.

They are sometimes referred to as "local hormones". They act like hormones on the body, but unlike "regular" hormones such as insulin, they are used where they are produced and not transported in the blood.

An eicosanoid produced from an omega-3 has a vastly different effect on the body than one produced from an omega-6, which is why it is essential that both omega-3's and omega-6's are present in the equine diet.

In general, the eicosanoids that are created from omega 3 fatty acids are going to produce less of an inflammatory response in the body than one from an omega-6. They are also going to produce less of a blood clotting response.

This lessened response is the reason that omega-3 supplementation is often recommended for horses suffering from arthritis, allergies, sweet itch, and other ailments that involve inflammation responses.

Eicosanoids produced from omega-3's are converted to eicosapentaenoic acid (EPA) and then decosahexaenoic acid (DHA). After that, DHA is converted to a group of substances referred to as the prostaglanding PG3 series. It is this conversion that is the reason for many of the benefits of omega-3's.

A recent study done on ponies predisposed to sweet itch found that dietary supplementation with feeds high in omega-3's (in this case flax) reduced the response to the fly that causes sweet itch.

Digestibility of Fats

Despite the fact that wild equines have little dietary fat consumption, fat is very well digested by the equine digestive tract.

When fat is added to forages, apparent digestibility is 55% of the fat. When it is added to grain mixes, that digestibility increases to 81%.

When straight fat is supplemented, the apparent digestibility is a whopping 95%.

The addition of fat to the diet appears to have little effect on the digestibility of other nutrients, including

  • Fiber
  • Calcium
  • Phosphorus
  • Magnesium long as the added fat makes up less than 15% of the total diet.

It appears that the digestion of protein before the small intestine may be slightly decreased by the supplementation of coconut oil or soybean oil at the rate of 0.5-1 gram per kilogram body weight per day.

However, the supplementation of corn oil (up to 233 g/kg of dry matter) had no effect on the digestion of protein, dry matter, or acid detergent fiber.

Excess Calories

It appears that small amounts of additional fat in the diets of most horses proves beneficial.

However, caution must be taken when supplementing fat to horses prone to metabolic issues, particularly insulin resistance.

In a 2001 study* shetland ponies that were fed to meet digestible energy requirements (15.5 MJ DE/100 kg body weight) showed an increased blood glucose level during an oral glucose tolerance test. The plasma levels of these ponies were about 40% higher than the control diet ponies.

In the same study, ponies that were fed in excess of their calorie needs showed a 25-fold increase in insulin concentrations in the blood after an oral glucose loading.

It appears that glucose intolerance and insulin resistance may occur in horses fed fat supplemented diets, particularly when they are fed beyond their calorie needs.

It should be noted that insulin resistance is a risk factor for laminitis.

Therefore, it is wise to use caution when supplementing fat to horses with known metabolic issues, as well as those that have low energy requirements.

If fat is supplemented to these horses, be sure that they are not intaking more calories than required.

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*Schmidt, O., E. Deegen, H. Fuhrmann, R. Duhlmeier, and H. P. Sallmann. 2001. Effects of fat feeding and energy level on plasma metabolites and hormones in Shetland ponies. J. Vet. Med. 48A: 39-49.