A look at the role of Omega-3 fatty acids in the equine diet, and how to determine the best source for your horse.
Omega-3 fatty acids are a particular type of fat. The name “Omega-3” refers to the chemical structure of the fat — particularly, the placement of a double bond in a specific location along the molecule. This gives Omega-3s high fluidity, which is of great benefit in one of their main functions — forming part of the structure of cell membranes. Because every cell in the body has a membrane, it’s no surprise that Omega-3s have many benefits! Some include immune and anti-inflammatory functions, and roles in brain and eye tissue. Needless to say, Omega-3s play an important role in your horse’s overall health.
When supplementation is warranted
One Omega-3 fatty acid is essential to the horse’s diet — alpha-linolenic acid (ALA). The term “essential” is used because ALA cannot be made by the body and must be consumed in the diet. Once in the body, ALA can be used to form other Omega-3s, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). You can think of ALA as the building block, and EPA and DHA as the functioning products. You can’t make the final products unless enough building blocks are available.
A horse maintained primarily on fresh pasture is able to consume large amounts of ALA, and such a diet contains substantially more Omega-3s than Omega-6s (see sidebar at right). However, the further you move away from this more natural diet, the lower the horse’s access to Omega-3s becomes. Hay has lower Omega-3 concentrations than fresh pasture, but still contains more Omega-3s than Omega-6s. Grains used in concentrate feeds, such as oats and corn, have even lower levels of Omega-3s, and to make matters worse, contain significantly more Omega-6s. The same is true for most plant oils.
For these reasons, horses who do not have access to fresh pasture may benefit from Omega-3 supplementation. This is particularly true when grain-based concentrates make up a large portion of the horse’s diet. Horses with inflammatory conditions or concerns may also benefit from added Omega-3s. While research has shown varying results, Omega-3 fatty acid supplementation may be beneficial for respiratory and joint inflammation, and for horses with metabolic conditions such as insulin resistance. Additionally, Omega-3s can be beneficial for exercising/performance horses and breeding horses.
Sources of Omega-3s
As previously mentioned, the most natural source of Omega-3s for horses is fresh pasture, which is rich in ALA. Besides being a better source of Omega-3s than grains and vegetable oils, fresh pasture is more conducive to the horse’s digestive tract, which is designed for small frequent meals of fibrous feed (i.e. grazing). However, pasture is not always a realistic option. When regular access to pasture isn’t available, and if the horse has some of the additional needs mentioned above, supplementation with other sources of Omega-3s may be beneficial.
Fish oil is one of the only natural sources of EPA and DHA. As such, it is typically considered the best Omega-3 supplement source, since it provides the EPA and DHA rather than just ALA. Getting horses to consume fish oil can be a problem, as horses often do not care for the taste. Adding a drop of peppermint oil and mixing the supplement in with grain can help mask the fishy flavor.
Recommendations on how much fish oil to feed vary widely (see sidebar below), so be sure to talk to your vet or an equine nutritionist before adding it to your horse’s diet.
Flaxseed is typically considered the best plant source of Omega-3s, containing a large quantity of ALA. “Flaxseed” and “linseed” are often used interchangeably, but while they are sourced from the same plant, they are processed differently. Flaxseed is typically used for feeds. The whole seeds are less digestible, so ground flaxseed or flaxseed oil are the typical supplement sources.
There’s often a misconception that flaxseed is toxic, but it has been shown to be very safe to feed to horses, even at rates much higher than those recommended for Omega-3 supplementation. However, the recommendation is that flaxseed be fed in the suggested preparations (ground seeds or oil) rather than soaking or boiling the seeds, as both of the latter have the potential to result in the formation of toxic compounds.
Chia seeds are another excellent source of Omega-3s, again in the form of ALA. Unlike flaxseeds, however, chia seeds have softer hulls and can be fed whole. While chia seeds are likely to have similar benefits as other Omega-3 sources, no scientific research has been conducted on feeding them to horses.
Selecting the best source
When considering Omega-3 supplementation for your horse, it is important to consider what type the supplement is providing. In horses, the process of converting ALA to EPA and DHA is inefficient and becomes less effective under stress conditions. For this reason, enough ALA must be provided to overcome this inefficiency, or additional EPA and DHA may need to be directly supplemented if there are concerns about a horse’s ability to process ALA. For horses that may have reduced metabolic function, such as seniors or those with metabolic conditions, a direct source of EPA/DHA is recommended. For other horses, sources of ALA alone may be sufficient, but supplementing the diet with a combination of EPA/DHA and ALA would be preferred. This could be accomplished with a combination of fish oil and pasture, or a commercial supplement that provides both EPA/DHA and ALA sources.
Another concern is rancidity. Because Omega-3 sources are high in polyunsaturated fats, exposure to air can quickly lead to rancidity. This is especially true for oils or ground products (like flaxseed). For these products, look for sources that have been stabilized. Typically, they’re stabilized with vitamin E, a fat-soluble antioxidant. You will see something like “mixed tocopherols” on a label when vitamin E has been added. In the case of ground flaxseed, if you choose to grind the seeds yourself, avoid storing them by ideally grinding them right before feeding. Store oils in the refrigerator when possible.
Overall, horses are designed to have a diet high in Omega-3s, as provided by fresh forage. Because not all horses are fed fresh forage, and some have additional needs for Omega-3s, supplementation with other sources can be beneficial.
Jennifer Moore, PhD is a Lecturer in the Department of Animal Science at NC State University with a background in Equine Nutrition and Physiology. Her research focuses on using exercise as a treatment for obesity in horses. As a lifelong horse person, with involvement in riding, competition, teaching, and research, she hopes that her research will one day help to improve the health and wellbeing of horses around the country.