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Four Must-Have Minerals In The Horse's Diet

Many horse owners take it for granted that their horse's diet is complete when feeding a diet of hay, or hay combined with a fortified feed. Hay is "incomplete" when it comes to nutrition, although it serves the need for fibre intake, protein, and calories. It is nearly void of vitamins, and always variable when it comes to essential minerals. Fortified feeds are sold as "generic" feed products and may or may not compliment the deficiencies in the hay. And, more importantly, what is described on the label is not necessarily "enough" for your horse. Take for example "selenium added" and Vitamin E, as well as "contains pre/probiotics". If you take a closer look at the amounts they usually do not meet what is needed for proper health.

So let's take a look at four minerals that are essential and are often under-supplemented:

Salt (Sodium Chloride): Sodium is important because it controls fluid balance in the body. Although Chloride is commonly found in forages, the amounts can vary considerably. This is where a hay analysis can help. It is safe to assume that all diets will be deficient of Sodium, hence the need for salt licks and loose salt. The best way to give your horse salt (and monitor intake) is to give your horse loose iodized salt at a rate of 1 oz (2 tblsp) per day in cool weather, and increase as needed in warm/hot weather. When choosing salt licks, look for plain white blocks; do not rely on mineral blocks to provide the needed nutrients for a horse.

Selenium: It is safe to assume that most of Canada's selenium levels are deficient in soils, unless you happen to live in the midwest provinces. Therefore it is highly recommended to add additional selenium into the diet besides what is given in fortified feeds. Also, blood testing can determine if your horse is deficient or not. Deficiencies in Selenium can lead to muscle issues, poor immunity and fertility, and inflammation. This is one of these minerals where too much is not a good thing. Toxicity may occur if too much is given at one feeding, or at amounts of 20 mg per day. Most supplements/feeds will provide 1-2 mg per day, however it is important to consider the "total' amount given from all sources of feeds. Is a natural source of selenium better? Studies have proven yes, so look for supplements that contain selenium yeast, complimented with natural Vitamin E, as the two work together for better bioavailability.

Iodine: Iodine is similar to selenium in that too much or too little is not beneficial. Iodine’s major role is to keep the thyroid gland functioning properly by producing adequate levels of thyroid hormone. Kelp is a popular way to supplement Iodine, but you should have blood work done prior to supplementing. Iodine toxicity are at about the same levels as for Selenium. A 500 kg horse will require about 3.5 mg per day from an iodine source.

Vitamin E: Although pastures are usually plentiful when it comes to this vitamin, levels in grains and hays are significantly deficient, Vitamin E supports optimal control of inflammation, protects muscles and red blood cells, and aids in good immune function. Deficiencies can lead to nervous system issues. Fortified feeds have relatively low guaranteed levels of Vitamin E and used more of an antioxidant for the product, not so much a supplement for your horse. Supplementation should be at the rate of 1200 IU per day but some studies are suggesting amounts as high as 5000 IU day. This would depend on exercise level and specific health issues such as tying-up where high levels are recommended. Vitamin E has little to no toxicity. It is best to feed this vitamin with a little oil or fat for better bioavailability to the horse.

Depending on where you get your hay, Zinc and Copper are often deficient as well. A hay analysis can determine where these levels are at before supplementing correctly.

We can all agree that all horses are not created equally; many have special circumstances that require attention when it comes to their diet. Although the NRC gives guidelines for horses in general based on weight, class, and activity level, other factors that require consideration for type and amount of supplementation include: stress (training, competing, shipping, etc), disease/injury, life stage such as senior years, rate of metabolism and genetics (easy vs hard keepers), weather, environment, management, housing and quality of feeds, forages and supplements.

For example horse in stress may require additional sources of Magnesium and Vitamin B's. Those that are recovering may require antioxidants such as Vitamin E and C. Senior horses slow down production of Vitamin C so may require supplementation. Look for low NSC and low calorie forages for Easy Keepers, while Hard Keepers usually require a fat supplemented diet. Cold weather and winter conditions require additional hay for horses to keep them warm and weight on. The quality of forages and feeds can greatly affect bioavailability of nutrients and therefore the overall condition, health, weight and performance of your horse. In the long run it is better to choose "quality" products to see the benefits.

Not sure where to begin with your horse's nutrition? I would suggest start with a hay analysis, collect feed tag information, gather up your supplements' information, and enter the results into the Feed My Horse Equine Nutrition Software. This software helps you assess your horse's current diet and helps you define an optimal diet. For more information visit my website at

Do you have a horse that requires a specialized diet? Do you need help in determining the best combination? Send an email to and share your story!


Jean Klosowicz, Equine Nutrition Consultant & Educator

Superior Equine Health and Nutrition Inc.

Bruce Mines, ON

fb: @SuperiorEquine


Healthy Horses. Happy Owners. Superior Results!

Superior Equine Health and Nutrition Inc. ~

The articles contained in this column are for the purpose of education and are not intended to take the place of proper veterinary care. They may be used in conjunction with such care to facilitate healing and maintain health of the horse.

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