Commercial Feeds For The IR Horse

A horse, like a person, can have a metabolic rate and genetic tendency toward obesity. Combine this with a lack of exercise, too many treats, overfeeding, even stress, and the easy keeper is at risk for hormone imbalances, the most critical of which is insulin resistance or IR. And insulin resistance helps set the stage for laminitis (founder). Take heart, though, there are practical solutions.

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Obviously, prevention is best, especially if your horse is showing signs of metabolic syndrome (see below). But if He’s already battling IR, you have a feeding challenge on your hands. In March 2012, we discussed hay for the IR horse. Here, we tackle concentrated feeds, aka grains, for the insulin-resistant horse.


Technically, concentrated feed sources should be only fed when the horse can’t otherwise hold his weight. Healthy horses often become obese because they’re given commercial feeds- even ones promoted for weight loss?they don’t need. These feeds are often high-calorie.

that’s because the cereal grains – oats, corn, barley, wheat, etc. – in most feeds contain high levels of starch. Oats are nearly 50% starch. Corn is higher. When digested in the small intestine, they break down to glucose, which is absorbed into the blood stream, leading to that unwanted insulin surge. So, what’s the answer? You “have to” feed grain, right? Well . . . read on.

COMMERCIAL FEEDS. Until recently, most commercially fortified feeds were cereal grains, molasses, soybean or corn oil, and few vitamins and minerals. Fortunately, there are now a number of low sugar/low starch options.

The good products are made with high-quality protein sources such as alfalfa meal or soybean meal, contain fats with anti-inflammatory omega 3s, and are fortified with vitamins and minerals. They are an excellent alternative for the insulin-resistant horse. However, you can’t just take the bag’s word for it.

Start by choosing a concentrated feed with no cereal grains or molasses and with a sugars-plus-starch total less than 12%. Be aware that some feed companies incorrectly refer to this as NSC. NSC equals starch plus WSC but not ESC. In terms of preventing insulin-related laminitis, ESC and starch have more of an impact on insulin secretion than WSC. See DE, NSC, WSC, ESC and more sidebar.

Keep in mind that commercial feeds are designed to be fed at the label’s recommended levels to provide adequate vitamin and minerals. Feeding less than the recommended amount will require you to supplement further to balance your horse’s nutritional needs.

We used the manufacturer recommended feed rates to compare the feeds, and we immediately noticed that many have high recommended feeding rates, above what your horse needs. This can lead to nutritional gaps.


Protein quality is enhanced by legumes such as alfalfa and soybean meals, as well as a mixture of forage sources. Various fibrous ingredients (e.g., beet pulp, wheat middlings, soybean hulls, etc.) also add to the protein’s quality.

Omega 3 fatty acids reduce inflammation, stabilize immune response, and improve blood vessel strength. Researchers at Colorado State University determined that omega 3 fatty acids improve insulin sensitivity, so they’re an important addition to your feed. Flax and chia seeds are excellent plant sources of omega 3s. Unfortunately, a common fat source in commercial feeds is soybean oil. With more than half its fatty acid content as inflammation-promoting omega 6 and only 7% anti-inflammatory omega 3s, soybean oil isn’t beneficial for reducing insulin resistance.

Sunflower seeds, as well as corn and wheat germ oils, are also high in omega 6s. Remember also that fats add a large number of calories. Look for feeds that have added omega 3s and an overall fat percentage of not more than 6%.

Magnesium is important for the insulin-resistant horse due to its ability to remove glucose from the bloodstream, thereby increasing insulin sensitivity. Five to 20 grams of added magnesium per day is worth considering.

Psyllium has been shown to lower blood glucose and insulin levels in horses. Though not typically found in horse feeds, it’s worth considering as an additional supplement for the insulin-resistant horse at a rate of 1/3 to 1/2 cup per meal.

BOTTOM LINE. The convenience of a commercial feed is tempting, but. . . .

Look closely at the feeding instructions. Are you feeding enough of it for your horse to benefit from all those added vitamins and minerals? Probably not, especially if you use it as a small carrier for supplements. Therefore, you still have to use supplements.

Your horse (and your wallet) might be better off if you prepare your horse’s meal using basic ingredients. It does take some care to ensure the right balance of nutrients, but it can be as simple as starting with unsweetened beet pulp or alfalfa pellets, then adding a comprehensive vitamin/mineral supplement (we suggest a good pelleted hoof supplement) along with flaxseed meal for omega 3 fatty acids (feed one-third the amount to ponies, donkeys, mules, and minis).

Remember: Horses become overweight mainly for two reasons: Overfeeding concentrates and inactivity. Common sense should prevail in helping an overweight, insulin-resistant horse lose weight: Respect your horse’s need to continually graze, feed a low-calorie, low-NSC hay, provide quality protein, omega 3s and magnesium, and remember the most important factor of all: Exercise! For more information, see sidebar IR sidebars.

Article by Juliet M. Getty, Ph.D., ( with contributions from Contributing Veterinary Editor Deb Eldredge, DVM.

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