Also known as linseed, flaxseed is produced from the flax plant and can be used to provide fat, protein, and fibre in the equine diet.
Flax products are cost-effective, calorie-dense and commonly fed to horses for weight gain or to support the energy requirements of high-performance exercise.
Flax seeds and flax oil are also sources of the omega-3 fatty acid, alpha-linolenic acid (ALA).  This essential fatty acid can be used to balance omega-6 intake and helps maintain skin and coat quality.
While consuming omega-3s is generally associated with health benefits, not all omega-3 fatty acids have the same effects on the horse’s body. Flax oil does not contain DHA or EPA, the two fatty acids associated with healthy inflammatory regulation and improved joint health.
The fatty acids in flax are vulnerable to rancidity when exposed to light, air, and water. Horses should be fed freshly ground flax or stabilized flax products to minimize health risks.
Flax for Horses
Flaxseed is produced by Linum usitatissimum, a flowering plant belonging to the Linaceae family. An ancient crop, flax has been cultivated for thousands of years for its fibre and oil content.
Flax is an annual plant that grows best in northern, cool climates. Canada is the largest producer of flax in the world. 
Multiple products are made from this plant including whole and ground flax seeds, flaxseed oil, and flaxseed meal – a by-product of flaxseed after the oil has been extracted.
Flax plants produce golden and brown-coloured flax seeds, both of which have a similar nutrient profile. Brown flax is the most common type of flax fed to horses.
Ground flax is more easily digested than whole flax because the hard outer shell is broken during grinding.
Nutritional Profile of Flax
Flaxseeds are nutrient-dense and contain approximately 40% fat, 30% fibre, and 30% protein.  They also contain B-complex vitamins, vitamins A and E, and minerals including magnesium, potassium, calcium, phosphorus, and iron. 
The cell walls of flaxseeds are also a source of phenolic acids, flavonoids, and lignans. These compounds are being researched for their anticancer and anti-oxidative properties.
Fatty Acid Profile
Flaxseeds are a rich source of essential fatty acids (EFAs). These EFAs must be obtained in the diet because they cannot be made by the horse’s body.
The fat content of flax seeds is comprised of polyunsaturated fatty acids (73%), monounsaturated fat (18%), and saturated fat (9%). 
Most of the fat in flaxseeds is in the form of two polyunsaturated fatty acids: 
- Linoleic acid (LA) – an omega-6 fatty acid
- Alpha-linolenic acid (ALA) – an omega-3 fatty acid
55% of the fat content in flaxseed is alpha-linolenic acid.  In comparison, linoleic acid makes up 16% of the fat content.
Benefits of Feeding Flax to Horses
Flaxseed and linseed oil can help support weight maintenance or healthy weight gain in underweight horses.
Flax is a great way to add energy to your horse’s diet without adding bulk. All fats provide 9 kcal (kilocalories) of energy per gram, making fat a much more concentrated source of calories than carbohydrates or protein.
Provides a Source of Cool Energy
Fat is considered cool energy because it can help to promote a calm demeanour in horses.  Swapping some of your horse’s grain ration for a fat source, such as flax oil, can help to prevent blood sugar spikes that may contribute to hot behaviour.
Fat is also more efficiently absorbed by the horse’s gut and produces less heat than protein or carbohydrate digestion.
Increase the Ratio of ALA:LA in the Diet
Including flax in your horse’s feeding plan can increase the ratio of omega-3 to omega-6 fatty acids in the diet.
Most commercial feeds contain more omega-6 fats than omega-3. In addition, hay tends to have lower levels of alpha linolenic acid than fresh pasture. 
Feeding flax as a supplemental source of alpha-linoleic acid may improve the fatty acid profile of equine diets, especially for horses being fed grain-based rations or with no access to pasture.
Contains Omega-3 Fatty Acids Support Health
Helps your Horse’s Coat Shine
Feeding more fat contributes to a shiny coat by increasing sebum production in the horse’s skin. Sebum is an oily substance that gives your horse’s coat a shiny appearance.
In horses, feeding higher levels of omega-3 fatty acids has also been shown to improve coat and skin health.
Horses consuming diets high in omega-3 had better coat quality scores with a smooth, glossy appearance. In contrast, horses consuming diets high in grains with elevated levels of omega-6 fatty acids had lower coat quality scores. 
Supports Horses with Skin Allergies
Research shows that the fatty acids in flax are beneficial for horses with sweet itch or recurrent seasonal pruritus (insect bite hypersensitivity to the Culicoides midge).
When horses were supplemented with one pound of ground flaxseed per 1000 lb of body weight for 42 days, their skin showed reduced sensitivity to allergens. 
May Aide in Nutrient Absorption
Whether the high fat content of flaxseeds or flax oil would have this effect in horses is unknown.
Provides a Source of Protein
Whole or ground flaxseed contains 18% protein. It has an amino acid profile that is similar to soybeans with high levels of the limiting amino acid lysine.
Protein is required to support growth, muscle function, and the building and repairing tissues.
Low in Sugar and Starch
Horses with metabolic dysfunction may also benefit from other plant compounds (phytonutrients) found in flax. 
High in fiber
Flaxseed is high in insoluble and soluble fibres, including pectin and mucilage. These water-soluble fibres form a soothing gel in the digestive tract.
The Role of Fatty Acids in the Equine Body
Flax is commonly fed to horses as a source of essential fatty acids (EFAs), which have several important roles in the horse’s body including:
- Improving the structural integrity of cell membranes
- Modulation of inflammatory processes
- Supporting vision & neurological function
- Promoting cardiovascular health
- Regulating gene expression
EFAs including linoleic acid (LA) and alpha-linolenic acid (ALA) must be supplied in the horse’s diet in an appropriate ratio to support the horse’s overall well-being.
This ratio is important because ALA is primarily converted into anti-inflammatory compounds whereas LA is mostly converted into pro-inflammatory compounds.
Omega-3 to Omega-6 Ratio for Horses
The ideal ratio of omega-3 to omega-6 fats in the equine diet has not been formally established. However, the natural diet of wild horses is known to provide more of the omega-3 ALA than omega-6 LA.
Fresh grass provides an excellent source of omega-3 fatty acids. Horses grazing fresh orchard grass, timothy, alfalfa, clover or fescue consume between two to four times more alpha-linolenic acid than linoleic acid. 
If your horse is primarily maintained on pasture, they are likely getting plenty of alpha-linolenic acid in their diet.
However, omega-3 levels are lower in cut hay. Depending on harvesting and storage conditions, levels of alpha-linolenic acid can decrease by almost half. 
Horses fed diets consisting of corn, grain, or other concentrates also tend to have significantly higher levels of omega-6s than omega-3s. These horses benefit from adding a source of omega-3 fatty acids to their diet to bring this ratio back into balance. 
EPA and DHA
ALA serves as a precursor for the polyunsaturated fatty acids, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid). 
EPA and DHA can be considered the active forms of omega-3 fatty acids in the horse’s body. These long-chain fatty acids are responsible for the health benefits typically associated with omega-3s.
EPA and DHA are converted into metabolic products (resolvins, neuroprotectins, and protectins) that reduce inflammation.  These substances interfere with the action of inflammatory compounds (prostanoids) and regulate inflammation. 
Research shows that DHA can improve metabolic function in horses. A study of eight horses fed a DHA-rich microalgae meal showed improved plasma glucose, insulin concentrations and insulin sensitivity. 
Some of the additional benefits associated with EPA and DHA in horses include:
- Improved reproductive health 
- Improved cognitive function in foals 
- Improved joint health and lameness scores 
- Improved respiratory health 
Is Flax a Good Source of Omega-3?
Is feeding flax a good way to provide your horse with omega-3 fatty acids and promote anti-inflammatory health benefits?
Flax contains alpha-linolenic acid, but not EPA or DHA, which are the active forms of omega-3. While ALA can get converted into EPA and DHA, the conversion process is not very efficient in horses.
Only approximately 10% of ALA is converted into EPA, and less than 0.1% is converted into DHA.  Because of this poor conversion rate, feeding ALA from sources such as flax oil does not increase DHA and EPA blood levels. 
To effectively increase levels of DHA in tissue and support anti-inflammatory benefits, it is best to provide EPA and DHA directly.
Sources of EPA and DHA that can be added to the horse’s diet include fish oil and microalgae. For example, Mad Barn’s w-3 Oil contains 1500 mg of DHA-enriched microalgae per serving.
Feeding Flax to Horses
Even though flax is not a source of EPA or DHA, it is still a beneficial fat source that can be added to your horse’s diet.
Several forms of flax or linseed products are commonly used in the equine diet. Options include feeding whole flax seeds, ground flax, stabilized flax, flax oils and flaxseed meal.
Whole Flax Seed
Unprocessed whole flaxseeds can be fed to horses, but they are harder for the horse to digest meaning there will likely be less absorption of the essential fatty acids.
Flaxseeds must be adequately chewed to break down the fibrous outer hull. Bacteria in the horse’s hindgut can help extract nutrients from whole flaxseeds, but some seeds may pass through the colon undigested.
Grinding whole flaxseeds before feeding improves their digestibility and increases nutrient utilization. If you grind your own flaxseeds, store them in the refrigerator in a sealed container to prevent the fatty acids from going rancid.
Ground Flax Seed
Ground flaxseed is the most popular form of flax fed to horses. It is produced by grinding or cracking whole flax seeds, improving the absorption and bioavailability of nutrients.
Once the protective outer hull of the flaxseed is broken, any exposure to light, heat, or moisture triggers an oxidative reaction that can make the fats go rancid.
Fats in food can undergo oxidation in which oxygen replaces hydrogen atoms in the fat molecule. This changes the properties of the fat which can be detected as changes in smell and taste. It will also produce free radicals, which are unstable molecules missing an electron from their chemical structure.  Free radicals can damage tissues throughout the body as they seek to obtain electrons.
Because the fatty acids in natural ground flaxseed are vulnerable to rancidity, this product has a short shelf-life and must be fed shortly after grinding.
Stabilized Ground Flax Seed
Stabilized flaxseed has been heat-treated to destroy the glycosidase enzyme that makes fats vulnerable to rancidity. Stabilized flax has a longer shelf-life compared to natural ground flax.
Stabilized ground flaxseed can be refrigerated after opening to extend its shelf life.
Oil extracted from flaxseeds provides a concentrated source of calories and essential fatty acids. Flax oil is ideal for adding fat to an equine diet without adding fibre or protein.
Unless stabilized, flax oil is vulnerable to oxidation and rancidity when exposed to air and light.
Flax oil does contain small amounts of naturally-occurring vitamin E – an antioxidant that helps to protect fatty acids from oxidation. To improve shelf stability, some flax oil products are made with added vitamin E and rosmarinic acid (rosemary extract).
Flax oils tend to be more expensive than buying whole or ground flax.
How to Feed Flax to Horses
Feed ground flaxseed or flax oil as these forms are more digestible than whole seeds. You can purchase stabilized ground flaxseed or grind whole seeds yourself using a coffee grinder or other suitable appliance.
Flax can be top-dressed on your horse’s ration or mixed with forage cubes or pellets.
The recommended amount of flax to feed your horse depends on their individual needs and your reasons for feeding flax. Higher feeding rates are generally used in underweight horses needing to gain body condition.
A typical serving size of flaxseed for horses ranges anywhere between 2 to 16 oz (60 grams to 450 grams) per day. Feeding rates for flax oil vary from 1 to 8 oz (30 mL to 200 mL).
The total fat content in your horse’s diet should be less than 8%. However, horses in heavy work may be fed up to 20% of their digestible energy requirement as fat. 
Feeding 80 grams of flax oil per kg of feed to horses at maintenance had no impact on palatability and actually improved fibre digestibility. 
Work with an equine nutritionist to determine the best feeding rate for your horse.
Introducing Flax to the Diet
Make changes to your horse’s diet gradually when giving any new feed, especially flax.
Horses need time to adapt to the higher fat content in their diet by increasing the production of digestive enzymes to break down fat.
Because flax is very high in phosphorus, ensure your horse’s diet contains sufficient calcium to maintain a proper balance between these two minerals.
Consult an equine nutritionist for guidance on mineral balance in your horse’s diet.
Horses on high-fat diets also benefit from increased intake of Vitamin E. Nutritionists recommend feeding at least 100 IU of additional natural vitamin E per 100 ml of oil in the diet.
Concerns About Cyanide
Some horse owners are concerned about feeding ground flaxseed due to reports of high cyanide content. But there is no evidence that feeding 1 lb of flaxseed daily causes health problems in horses.
Flaxseed contains cyanogenic glycosides (natural plant toxins) and the glycosidase enzyme, which are precursors for cyanide production. These two compounds are found within the whole flaxseed but do not react with each other if the seed is intact and dry.
When flaxseeds are exposed to air (from chewing or grinding) or water, the cyanogenic glycosides are activated by the glycosidase enzyme, and cyanide gas is produced.  Cyanide is toxic and can have harmful effects in large amounts.
Fortunately, the horse’s stomach acid inactivates the glycosidase enzyme and prevents cyanide from being produced in quantities large enough to cause a health concern.
To minimize cyanide formation when mixing with a moistened feed, add ground flaxseeds last and feed immediately.
Alternatively, choose a commercially stabilized ground flaxseed product for your horse. Stabilized ground flax is treated with heat to deactivate the glycosidase enzyme. 
Boiling water also renders the glycosidase enzyme inactive, but this is not recommended because it also damages proteins and other nutrients in flaxseed.
Alternative Fat Supplements for Horses
In addition to flax oil, many other fat supplements are used for horses. Some alternative plant-derived oils include:
Compared to these alternative fat sources, flax is higher in ALA and haa a better omega-3 to omega-6 ratio.
Camelina oil is derived from the camelina sativa plant, sometimes called false flax. While it is advertised as an ideal source of omega 3s for horses, it actually has a lower concentration of alpha-linolenic acid than flax.
Camelina oil is composed of 35 to 40% ALA, compared to 57% ALA content in flax oil. Flax oil is also more cost-effective than camelina products. 
The omega-3 content of flax oil consists solely of ALA, with no EPA or DHA. While a small percentage of ALA is converted into these active forms of omega-3 fatty acids, the conversion rate is too low to promote the physiological benefits associated with EPA and DHA.
Mad Barn’s w-3 Oil is an alternative fat supplement that provides high levels of the DHA derived from microalgae. W-3 Oil is also formulated with 1500 IU of natural Vitamin E per serving in a flax and soybean oil base.
For horse owners looking to supplement omega-3s in support of joint health, respiratory function, reproductive health, and modulation of inflammation, w-3 Oil is a more effective choice than flax oil.
Feeding flax to horses can support healthy weight maintenance, coat quality, skin health and exercise performance.
Flaxseed or linseed is an excellent source of essential fatty acids required in the equine diet. Flax oil has a similar ratio of alpha-linolenic acid to linoleic acid as fresh pasture grasses.
Feeding flax can help maintain a healthy omega-3 to omega-6 ratio, especially for horses eating commercial grain-based feeds or primarily maintained on hay.
However, flax does not contain EPA and DHA, which are the active forms of omega-3s associated with anti-inflammatory benefits. The horse can convert some ALA into EPA and DHA, but the conversion rate is very low.
Research shows that flax oil is less effective for increasing omega-3 levels in the blood than feeding horses EPA and DHA directly. Fish oil and Mad Barn’s w-3 Oil can be used as alternatives.
Consult with an equine nutritionist for personalized guidance on adding fat sources such as flax oil to your horse’s diet. Submit your horse’s information online for a free consultation and diet balancing.
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