What Every Horse Owner Should Know

By Madeline Boast, MSc. Equine Nutrition

As a horse owner, you may be curious about the potential benefits of adding omega-3s to your horse’s diet. Do all horses need them? Should you be adding them to your horse’s diet? Are there well-reported benefits? Understanding the requirement for fatty acids in the equine diet, like omega-3s (O3s) and omega-6s (O6s), and the well-reported health benefits of them is important when considering supplementation.

The horse is not able to synthesize omega-3 fatty acids on their own. Therefore, these nutrients are essential to the horse and must be provided in the diet. They play important roles in cell membrane function as well as structure, and are important for inflammatory responses, immune function, muscle contraction, and blood clot formation.

Omega-6s are another type of essential fatty acid and play an important role in inflammation and swelling. They are also essential for health; however, when oversupplied in relation to omega-3s, they can result in increased inflammation in the body. 

Related: Understanding Equine Dietary Supplements

The Metabolic Pathway

When beginning to explore omega-3 supplementation, it is critical to understand that there are multiple omega-3 and omega-6 fatty acids originating from different feedstuffs and having differing biological activity in the body. The plant-derived fatty acids that are present in the equine diet must go through an elongation metabolic process prior to being available for the horse to use. Hence the biological activity differs depending on where that omega fatty acid is in the elongation process.Alpha-linolenic acid (ALA) is typically the most prevalent omega-3 in equine diets as it is plant-derived and present in forages. However, research generally focuses on the omega-3s eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) which is at the end of the metabolic pathway. These omega-3 fatty acids are more bioavailable than ALA.

The omega-3 at the start of the metabolic pathway is ALA. The omega-6 at the start of that metabolic pathway is linoleic acid (LA). These starting fatty acids must be elongated prior to being of use to the animal. Delta-6-desaturase (D6D) is the enzyme that begins this elongation process for both ALA and LA.

As both omega-3 and omega-6 fatty acids rely on the same enzyme in their metabolic pathways, and because there is a finite amount of this enzyme available to use, it becomes rate-limiting. Therefore, to maximize potential health benefit, it is recommended to provide omega-3 fatty acids that are further along in the elongation process and skip this limiting step.

This reduces the issue of ALA and LA having to compete for the same enzyme. Due to the competition for the enzyme that facilitates elongation it is important to be aware of the balance of these nutrients in the diet.

Related: What Is Teff Hay for Horses? 

Balancing Omega-3s and Omega-6s

Research has not yet established an optimal ratio for omega-3 to omega-6 content in the equine diet, but it is hypothesized that about 1:1 is ideal. Horses evolved to consume large amounts of forage, and forages contain more omega-3 than omega-6 content. Grains are the opposite, containing more omega-6s.

Horses that are maintained on forage-first diets will generally have more omega-3 than omega-6 content in their diet. Forages provide low levels of fat with the typical range being about two to three percent. Even though the overall percentage of fat in hay is low, the horse consumes a large volume of hay daily, and generally a much larger volume than any supplemental feeds or concentrates. Even when omega-3 supplements are added, the forage often remains the most vital source of plant-derived omega-3s as the volume consumed is so great.

Horses naturally evolved to consume large amounts of forage, which contain more omega-3 than omega-6. In contrast, grains have a higher omega-6 content. Photo: Shutterstock/Anastasija Popova

When grain-based concentrates are added to the diet, the omega-6 content of the diet increases. Omega-6 fatty acids are often presented in a negative light, and despite what marketing may lead you to believe, they are not bad for your horse. In fact, both omega-3s and omega-6s are required to support optimal health in horses.

Most horses that are maintained on a forage-based diet with adequate vitamin and mineral supplementation do not require an omega-3 supplement, as their forage will be an adequate source. However, there are a multitude of studies illustrating health benefits of omega-3 supplementation, specifically in regard to reducing systemic inflammation in the body.

Inflammation is a healthy and important process in the body. For example, when a horse is exercised, inflammation plays a key role in the body returning to homeostasis afterwards. When discussing dietary modifications to reduce inflammation, the focus is on systemic inflammation, which persists over time and can become a concern. To optimally supplement your horse and successfully reduce systemic inflammation, both the omega-3 to omega-6 ratio as well as the type of omega-3 are important factors to consider.

Related: What is Grain-Free for Horses?

Omega-3 Sources

As previously mentioned, not all omega-3s are equivalent in their biological activity. The sought-after omega-3s are EPA and DHA, which result from elongation of plant-derived omega-3s, or can be fed directly to skip the elongation when derived from marine-based sources such as fish oil. The primary challenge when feeding marine-based omega-3 sources is that horses are herbivores and do not find them palatable. As with any feed or supplement, if the horse is unwilling to eat it, there will be no health benefit.

When deciding on a product, understand what the omega-3 to omega-6 ratio is as well as the type of omega-3 in the product. Choose a fat source that has a balanced ratio for your horse considering his entire diet and health status. Photo: Shutterstock/GoodIdeas

The first consideration when choosing a fat source to add to your horse’s diet is the omega-3 to omega-6 ratio of the product. Fat supplements are commonly added to equine diets for calorie content and to improve coat health. Now understanding the omega-3 to omega-6 ratio, identifying which fatty acids are present in the product is important to make the best choice.

For example, sunflower seeds and oil may be fed as a source of fat in the diet; however, the omega-6 content far exceeds the omega-3 content with a ratio of about 200:1, omega-6 to omega-3. This may not be an issue for a horse that is on a forage-based diet without a large amount of grains; however, if you are trying to reduce systemic inflammation, or have a horse that is on supplemental grain-based products, it is recommended to opt for a fat source that provides a more balanced ratio, or is higher in omega-3 than omega-6 content.

Linseed oil, also known as flax oil, is one of the most popular omega-3 sources fed to horses. It has an omega-6 to omega-3 ratio of about 1:4. Research published in 2002 by O’Neill et al. illustrated that horses fed one pound of flaxseed per 1000 pounds of body weight for a duration of 42 days had reduced inflammation and a significant reduction in skin response to an allergen.

As flax oil is a plant-based omega-3 source, it would be providing ALA, which as previously discussed is at the start of the metabolic pathway and must compete with omega-6s for the elongation enzyme D6D. This is why many products will market their EPA and DHA content to skip that rate-limiting step and improve the bioavailability. A 2010 study from the University of Florida by Vineyard et al., 2010 was unable to illustrate a modification in the EPA or DHA levels in the blood when ALA was supplemented to the horses.

Therefore, the source you choose when adding omega-3s to your horse’s diet will impact the health benefits you see. A study completed at the University of Guelph by Burron et al., 2023 compared camelina, flax, and canola oil. The horses were provided with 370 mg of oil/kg body weight daily. Both camelina and flax have greater omega-3 content than omega-6, and canola oil has a greater omega-6 content. The fatty acid profiles in the plasma reflected the differing fatty acid profile of the oils provided. For example, plasma ALA was greater for horses supplemented with flax oil than canola oil and the omega-6 to omega-3 ratio decreased over time for both camelina and flax oil groups.

For horses that need more calories to maintain a desired body weight, or those at risk of developing ulcers, fat sources with greater omega-3 than omega-6 content can be a good option. Photo: iStock/DinaSigtrix

Related: How to Accurately Feed Your Horse a Forage-Based Diet

Health Benefits

There are many well-reported benefits to omega-3 supplementation for horses, and new research expanding our knowledge on this topic continues to be published. From improved respiratory function, improved skin health, and decreased joint inflammation, the health benefits are numerous and backed up by science.

A 2009 study by Manhart et al. reported that horses supplemented with EPA and DHA had lower prostaglandin E2 levels in their plasma, which is an omega-6-derived pro-inflammatory pain producer. This research suggests that supplementing EPA and DHA could be beneficial in horses that have osteoarthritis. Additionally, DHA-rich microalgae have been shown to decrease the inflammatory response in joints and in turn improve lameness scores.

In addition to positive research on reducing inflammatory responses related to osteoarthritis, a 2014 study by Nogardi et al. demonstrated that daily PUFA (polyunsaturated fatty acids) supplementation for two months improved the clinical signs of chronic lower airway inflammatory disease by about 60 percent. The DHA amount supplemented to these horses ranged from 1.5-3 g daily.

In addition to the research showing benefits to certain health issues, adding fat to the diet for calorie supplementation is a popular practice. For horses that tend to be excitable on supplemental grains and concentrates, but require more calories to maintain a healthy weight, fat sources can be a good option. This is also recommended for horses that are at a greater risk of developing gastric ulcers as you can add calories to the diet without increasing the starch content. In these cases, a fat source that is providing EPA and DHA is not necessary but opting for a fat source that has a greater omega-3 than omega-6 content is recommended.

Related: Why Hay Analysis Is Essential for Your Horse's Nutrition

Applying the Science  

If your horse is on a forage-based diet that does not have a large inclusion of grains or omega-6 rich ingredients, you do not need to add an omega-3 supplement. However, if your horse struggles with any health issues that involve increased inflammation, such as osteoarthritis, heaves, or allergies, the current research supports supplementation. If your horse experiences any of the previously mentioned health issues, it is recommended to discuss optimal omega-3 supplementation with your qualified nutritionist.

Linseed oil, also known as flax oil, is one of the most popular omega-3 sources fed to horses. Photo: Dreamstime/Airborne77

First and foremost, when deciding on a product, understand what the omega-3 to omega-6 ratio is. As previously stated, many fat sources provide more omega-6s than omega-3s, which would not be effective at lowering the overall dietary ratio. The exact ratio of the product may not be publicly available, so in these cases, read the ingredient list to evaluate where the omega-3 and omega-6 fatty acids are coming from. For example, is the product a flax oil base (more omega-3s) or a soy oil base (more omega-6s).

Secondly, in addition to the ratio of omega-3s to omega-6s, the type of omega-3 is critical to consider. Adding a product that is providing EPA and DHA, and therefore skipping the rate-limiting elongation step, is beneficial. These products have marine-derived omega-3s, so note that palatability may be an issue.

Take Home Message

Both omega-3 and omega-6 fatty acids are essential to equine nutrition. When deciding whether to supplement your horse beyond what their hay provides, it is important to take a comprehensive approach by evaluating their entire diet and health status.

Related: How to Adjust Your Horse's Diet as They Age

Related: 8 Steps to Prevent Colic as Horses Transition to Hay

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