How to Use the Glycemic Index to Increase Health and Performance

How to Use the Glycemic Index to Increase Health and Performance

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There are many ways in which low glycemic feeds can improve our horse’s health and I’m happy to have guest Mark DePaolo, DVM share how to do that below!


Good nutrition is integral to allowing a performance horse to achieve its highest potential. Thinking about food as energy and how various feeds affect the body is extremely important. Diet actually plays a critical role in many equine health issues such as ulcers, tying up, allergies, laminitis and a compromised immune system.

Complete feeds (commonly referred to as ‘grain’) are often thought to provide everything required by performance horses. Most of these offer the type of quick burning energy you get from a candy sugar high, rather than a steady supply of energy obtained from feeding rice bran, beet pulp, and forages like alfalfa.

The digestive system of the horse is designed to continually ingest fiber and use it as a slow burning form of energy. Unfortunately, many of today’s show horses are being fed a consistent diet of starchy carbohydrates and sugar because it is easy for the owner, rather than nutritious for the horse.

Complete Feeds
Complete feeds or ‘grain’ are high in non-structural carbohydrates (starch), which horses do not adequately process in high quantities. Therefore, some of it passes through the stomach and small intestine undigested before it can be broken down by fermentation in the cecum and colon.

Once starch reaches the large intestine, it lowers pH levels and provides a feast to bacteria. This creates lactic acid which causes discomfort and muscle soreness, as well as increases the risk of colic and hindgut acidosis. The change of environment can also cause ‘good’ bacteria to die. When that happens, endotoxins are released into the gut, to be absorbed by the bloodstream. Those endotoxins can lead to laminitis.

Horse eating sweet feed.

It is important to read the label on the feed bag to understand HOW MUCH is needed at each meal to achieve the stated daily requirements of vitamins and minerals. Some ‘grains’ require you to feed as much as 10 POUNDS a day for horses in moderate to heavy work. It is extremely difficult for the horse’s digestive system to process that large amount of starch while under stress.

Also, if you are accustomed to measuring grain rations with a two pound scoop, that is often less than the recommended amount. Your horse will not receive enough vitamins and minerals to meet his nutritional needs. This can lead to the inability to fight off illness and make your horse more prone to injury.

Avoid ‘grains’ that contain molasses, corn, soy, by-products or middlings. These can be hard to digest, usually contain high amounts of herbicides, and may induce an allergic response from the immune system.

Glycemic Index
The best way to evaluate feeds is by using the Glycemic Index. The GI will help you to determine if a particular ingredient will elevate the blood sugar level, creating an insulin spike once ingested. It is also helpful for ranking and comparing what you are feeding your horse.

Whole oats act as the standard glycemic index feedstuff with a value of 100. A feed with a glycemic index value over 100 produces more blood glucose in a given amount of time than whole oats, and a feed with a glycemic index of less than 100 produces a lower blood glucose response. Look for feeds with a value of 50 or lower to provide the best nutrition.

Glycemic Index

Think of the glycemic index as the ability to choose which road you want to trailer your horse. A high glycemic index feed is like a steep mountain pass, while a lower GI is a straight highway. The later is much easier to navigate and less stressful for your horse.

Non-structural carbohydrates that break down quickly during digestion and release glucose rapidly into the bloodstream will have a higher glycemic index value. Always read the label and check to see if there are high GI ingredients.

Most grain concentrates are full of starch – that is any form of feed that is swiftly broken down and turned into blood sugar, creating an insulin spike. Both non-structural carbohydrates and sugar are considered starches. Comparing this to human food: non-structural carbohydrates (starches) are like potatoes and pasta; structural carbohydrates are more fibrous foods like black beans and broccoli.

Read your feed label and avoid these ingredients…

  • Corn (whole, cracked, ground), corn gluten, corn germ meal
  • Wheat, wheat bran, Wheat middlings
  • Oats (whole, crimped, rolled), oat mill by-product
  • Barley (whole, crimped, rolled)
  • Rye
  • Sorghum
  • Processed grain by-products
  • Brewers dried grains
  • Distillers dried grains


  • Molasses
  • Cane molasses
  • Fructose

Don’t be fooled by complete feeds that tout low non-structural carbohydrate stats. Although these have a lengthy list of vitamins and minerals, often the first 2-3 ingredients register high on the GI index scale. Additionally, these feeds usually have a sweetener additive such as molasses.

Sweet feed.

If molasses is included, that constitutes a sweet feed, and will certainly spike blood sugar. Molasses is the most common feed additive because it makes feeds more palatable and easier to package. It also smells good to the person feeding it. Be aware that these high-sugar feeds cause increased levels of acid production during digestion and promote ulcer formation.

Better Choices
Rather than offering your horse a starchy, sugary complete feed, consider a combination of hay pellets and rice bran or beet pulp (without molasses). If you are feeding grass hay, then alfalfa pellets are a great choice because they have a low GI and provide a lot of fiber. If your forage of choice is alfalfa, then use grass pellets instead.

Beet pulp is made from the fibrous portion of the sugar beet after the sugar has been removed. It is an excellent source of digestible fiber and is low on the Glycemic Index scale.

Rice bran is rich in dietary fiber and essential fatty acids. When your horse needs a little extra weight, increase the amount of rice bran to provide more fat. Additional healthy sources of fat include flax, olive and rice bran oils as a top dress over the alfalfa or grass pellets.

Horse eating hay.

With this approach, you will also need to provide a good quality complete daily vitamin and mineral supplement. Also, feeding smaller meals more often is better for your horse than just twice a day. This ensures there is always food in the stomach to prevent unchecked acid from irritating the stomach lining, which can lead to ulcers and a sore back.

If you need to make a feed change to reduce starch in the diet, it is best to slowly transition over a two week period. This will allow the hindgut flora to adjust to the new food. An abrupt change in ‘grain’ or hay can slow digestion which causes increased fermentation, gas, diarrhea and sometimes colic.

Wrap Up
While complete feeds may allow horses to look good in the short-term, over time horses are likely to develop metabolic issues and digestive health concerns due to the high starch and sugar content many complete feeds contain.

The Glycemic Index allows you to evaluate your feed program so that you can provide the best nutrition possible. It is an easy way to help prevent illness and will allow your horse to thrive both mentally and physically!


Click here to learn more about Dr. Mark DePaolo. For information on the services and products offered, including Horse Hair Analysis, visit

For more specific information on how to detect and correct mineral imbalances and metal toxicities with Horse Hair Analysis, click here.

For further research, you’ll also enjoy the DEC Horse Health Library as well as Dr. DePaolo’s YouTube videos on do-it-yourself ulcer detection, resolution and more.


Remember, nutrition is the foundation of health.

How will YOU be making your horse’s foundation stronger in the New Year?

Let’s hear it in the comments below!

10 replies
  1. Sandy Hickey
    Sandy Hickey says:

    🙂 I am sitting here shaking my head yes, smiling and saying to myself YES, finally, someone that can make a real impact on barrel racers, or any real performance horses, not just barefoot trail horses.
    Once again the timing on which either I open your articles or you share them, or both is unbelievable for personally. Most of the time I don’t even comment, although I am usually so darn excited, if I did try to reply, I would be here all day, since I now know, I am an introvert that cannot settle for mediocre responses or answers, I have to dive in deep! So, a quick thank you for finally an answer I can give my husband as to why, I MUST research everything! LOl
    Anyway, aaaaaahh horse nutrition! Besides barefoot trimming, training and competing, my passion! While I have known about the long and short term negative side affects from feeing grain for quite some time, it wasn’t until last spring that I started my journey with improving our horses diets, finally! You see, s an introvert, haha, I cannot just make a change by what someone “tells” me is good for my horses, I HAVE TO learn WHY! So making small changes as I went, learning along the way, researching products, understanding ingredients, bla, bla, bla you know how it is! LOL I am finally grain free and have my new nutrition program in place. Of course, that doesn’t mean I stop learning.
    Our horses have never looked better, and changes in their even temperaments are slowly being noticed as well, more with some than others. 🙂 And they looked good before, but not like they do now. Of course I always look at the feet first and work my way up! LOl yep, they look amazing and getting better all the time!
    THANK YOU for this and again what you do. I was not blessed with the gift to interact with people as well as I do animals, but I am SO thankful God blessed people like you, to do this part. I hope that many will see this and trust your knowledge to at least start a change. It doesn’t have to be a lot, just being more aware, open minded and willing to learn and change old habits.
    I am super anxious for the racing season to be in full swing again so I can see the results in the arena as well. So far, so good with the last two runs I have been able make on my one mare. Two, CONSISTANT, 1D runs, putting me 3rd so far in the average of a winter series. Just saying! All the hard work is always worth it to me. 🙂
    Thanks Heather!

    • Heather Smith
      Heather Smith says:

      Thanks Sandy. It’s great to hear from folks who question the status quo and aren’t convinced to do what everyone else does “because it’s always been done that way!”

      We dropped oats from our horse’s diet a couple months ago and now feed Renew Gold, which has rice bran, flax and coconut. All our horses are doing great but the biggest change has been in Craig’s gelding, Frosty. He had been sidelined with ring bone for years, and had what I now believe was sub-clinical laminitis, which as you know, is actually quite common.

      I figure something is just not right if there is chronic inflammation, and it’s so crucial that we keep digging to take care of it at the source vs. only medicate. Diet is a HUGE part of that and I’m thrilled to report that Frosty’s first day of re-conditioning (yesterday) went well – he is now sound enough for riding!

      His comeback is nothing short of a MIRACLE – made possible through Dr. DePaolo’s low glycemic index feeding recommendations!

      • Sandy Hickey
        Sandy Hickey says:

        So happy for Frosty! It is amazing the positive changes that can occur in the hoof and body when the right diet, movement, lifestyle and trim are put into place! I pray Frosty will have continued healing!
        Dr. DePaolo’s has excellent nutrition and horse health knowledge and advice. There are so many great resources out there.
        My horses are healthier and happier than they have ever been. I just got done RAVING to my husband about how good they are looking feeling and how healthy their feet are looking and growing! It is exciting in deed. Thank you again for all you do and your willingness to share and inspire!

        • Heather Smith
          Heather Smith says:

          It’s my pleasure to share, Sandy! I’m so happy to hear your horses are THRIVING – it’s SO rewarding when there are obvious signs pointing to the fact that they are Happy AND Healthy!

  2. Kristen
    Kristen says:

    I agree! Finally someone touches on the “feed” subject that not everyone likes to talk about. Everyone has their own opinion and what works best for them which is great, but I have yet to find a “feed” that I just absolutely LOVE. I’ve thought about trying the rice bran and beet pulp, something better for my equine partners is always on my mind. I have done some research but I think I just confuse myself more than add to my knowledge, nothing that has to do with horses is ever easy. I shall continue my research on portions and what works best as far as minerals go. I want to provide the best for my horses without breaking the bank….if there is such a thing :). I’m in the process of treating 2 of my horses for ulcers and using a preventative in another horse, it would be nice to have a feed that help not cause ulcers. Any suggestions on where I could get an idea of portions for beet pulp and rice bran would be appreciated. My horses are definitely not hard to keep weight on.

  3. Alyssa S.
    Alyssa S. says:

    For the past year now I have been feeding soaked alfalfa cubes, and rice bran pellets ( also feed renew gold ( rice bran, copra meal and flax mix) if extra weight is needed, or even rice bran oil or coconut oil) as well as grass hay ( usually free choice, the horses also have access to clean water, minerals and salt 24/7)and what a difference!!! It’s less expensive than those $30 a bag complete feeds. Plus it adds a good overall weight to my horses without having to feed such a large quantity of grains at every meal! It works on all my horses young and old and adds a topline! That’s something that complete feeds never could accomplish for me. And my old gelding with ulcers feels soooo much better on this diet! I have been researching diets for both myself and my horses for years, finally figured out what works for my horses, It’s so nice to read articles like this that give me confidence that I am on the right track when it comes to my horses health! Plus did I mention it makes their coats, manes/tails, and hooves look amazing?? I’m a firm believer in the low GI method you could say in the least!! 😉

  4. Lisa
    Lisa says:

    I feed alfalfa and Timothy pellets. Grass pasture 24/7. My horses do great on this. My question is what about a mare with a 2 month old baby and a yearling? I have them on omalene 300. Yep sugar molasses


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