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Is My Horse’s Grain Creating Health Problems?

Grain.  They are a staple in the horse community.  Processed or commercially available grain products are the most popular and there seems to be a grain blend for almost any health or performance issue. Considering the popularity of these commercial grains and the concurrent rise in health problems in horses, you have to ask whether if you are truly doing good…or are you maybe doing harm?

Scoop of whole oats and corn grain for horse
Scoop of whole grain for horse

When I look back on my veterinary career, spanning 23+ years, I have to notice trends in equine health care. In the first decade of my career, most horse owners utilized whole grains or sweet feeds. In the second decade, I began to notice more advertising for specialized commercial feeds, pelleted versions and complete feeds, which owners were buying.  There were diets for the overweight horse, the elderly horse, the performance horse and even the recently weaned horse. At that time, I was interested with the new diet selections, but didn’t buy into the mentality, especially as I began to notice the impact on our patients. What we saw in our practice, over time, was an increase in laminitis cases, increased bleeding in competition horse, more tendon problems and performance related issues.  We also saw a rise in joint complaints and growth problems in young colts.  Was this coincidence?  I had to seriously wonder.

In the past few years, I have become increasingly concerned over the impact of these commercial grain products.  I look back to years past, into the 1970’s, and try to gather as much information as I can regarding what some high level equine athletes were fed.  Could it be a partial explanation for why Secretariat and many others competed to the high level that they did? In those times, commercial feeds were not readily available, at least to the degree that they are today. Most owners simply fed whole oats, maybe with some carrots added in.  Some would feed sweet feeds in addition to the whole oats.  I believe, based on my findings, the rates of catastrophic injury on the race track and bleeding were much lower as well.  I talked recently with a TB trainer from Peru, noting that difference between how he fed his race horses 30 years ago, compared to today.  He also noted in hindsight, that the number of horse with bleeding and foot issues in his barn had increased. Again, is this coincidence?

Is there a difference between what they were doing then and what we are doing now?

What is a grain for a horse and what is its purpose?

The first question we have to ask is whether grains are absolutely necessary for the horse?  If we turn a horse out onto a mature pasture with grass that has headed out with seed production, they do not go to those seed heads and consume to their heart’s content.  Instead, most actually walk away to a part of the pasture with less grass height, seeking the more lush leaf component.  To me, this is an indication that although some will eat some seed heads, it is not their preference.

Grains are a great source of carbohydrates, which are used as a fuel for the body to produce energy. They are therefore helpful and often vital in cases of competitive equine athletes to give them that fuel.  However, in the horse, we have to take into consideration the metabolism of carbohydrates and what impacts that can have.  Most studies have indicated that in the horse there is a finite amount of starch that can be processed in the small intestine. Anything over this amount passes through to the hindgut for fermentation.  To use an example, oats generally have a limit of 2 lbs per feeding, based on the average starch content.  Anything above that amount will drift to the hindgut.

Carbohydrates also impact blood sugar level, because carbs are sugar in one form or another.  There are ‘good’ carbs and there are ‘bad’ carbs.  When we discuss carbs, we need to look at the glycemic index (GI), which is the rate at which that food can raise blood sugar.  This glycemic index is really dependent on the complexity of the carbs in the food.  The more complex, the more time needed to break down and thus, the less likelihood of creating a sugar or insulin spike.  Plain sugar, being present as fructose or glucose, is going to have a high glycemic index (100), due to the fact that it is already broken down into the desired form.   Whole oats, on average, have a glycemic index of 55.  The more processing we do that grain, the higher the GI index.  If we create an ‘instant’ oatmeal, that GI index rises to 79 or higher.  So, the more processing, the higher the GI index and impact on blood sugar and insulin.  This may also apply to the highly processed grains on the market today.

So, what is the big deal?

What is the potential impact of a grain on horse health?

The first thing we need to look at is the impact on blood sugar and insulin.  With any grain meal, we do expect the blood sugar to rise, due to the carbohydrates that are present. However, what we don’t want is a quick rise in blood sugar that also equates to a spike in insulin levels.  When this happens, it creates a wave of energy for the horse, but it is short lived. The glucose level can drop quickly as can the insulin levels.  If this is kept up, there will be spikes and drops in both glucose and insulin throughout the day. This is not healthy for the body and contributes to confusion of sorts, on a cellular level, impacting overall performance and even health for the long term.  It can lead to insulin regulation concerns, which then contributes to metabolic conditions, laminitis and impact foot and tendon health.  The more processed the feed, the higher the GI index potentially.  Thus, there is potential that the more processed the feed, the more room there is for cellular damage due to these highs and lows.

The second thing we need to look at is the volume of grain fed to the horse.  I am astounded at times how much grain some owners will feed, especially on the race track.  We have to keep in mind that as noted above, there is a finite limit as to how much carbohydrates can be processed in any one meal, with the remainder drifting over the hindgut.  In some cases that I consult with, owners are feeding by the quart, with 6-8 quarts per day.  In today’s day and age, they are feeding commercial, processed grains.  When I read about Secretariat, I note he was fed whole oats, average of 6 quarts per day.  If we split that up into 3 feedings, that would equate to 2 quarts per feeding.  I’ve never weighed out a quart of oats, but my sources tell me that 1 quart is equal to approximately 1 lbs.  So, in this instance, we are staying within that 2 lbs limit of starch intake, when it comes to oats.  By adhering to this, we have less of a likelihood of carbohydrate drift into the hindgut.

The big concern with carbohydrate drift into the hindgut is that these carbohydrates become media for fermentation.  This then leads to changes in the microbial populations in the hindgut, bad groups tend to overgrow, while beneficial bacteria die off.  It shifts the whole dynamics of the horse and health. Acidosis is created, inflammation is instigated and digestion is impacted.  This can then impact the entire body from tendons, to feet to performance issues and bleeding (EIPH). In many, we also begin to see evidence of leaky gut and immune impairments.  In a study we did in 2015, we cultured the feces of several horses, demonstrating that indeed, there were overgrowth problems due to feed practices, which correlated with ongoing health problems in that patient.  Here is a link to the initial study, and a link to the follow up study we did after dietary modifications.  In the study, we noted an overgrowth of lactic acid bacteria, specifically Lactobacillus, which is confirmed in other published studies.  The irony is that many horse owners are supplementing this bacterial strain through fortified feeds or probiotics on a daily basis.  Could they be creating more harm?

Does a horse grain provide vitamins and minerals?

The final concern that I have is that most owners using processed feeds are feeding high volumes because they feel that feed is necessary for vitamin/mineral supplementation.  In reality, grains are a source of macro and micronutrients, but do not naturally provide 100% of what is needed each day. We don’t want them to, as they are only a small part of the equine diet.  A very small part!  A horse was designed to get their nutrients from forages…not grains. The processed feeds have micronutrients added to them, in a spray-dried on synthetic form.  This is not natural. Thus, many owners feel the only way to satisfy the nutrient needs of their horse is to use these grains. Several problems then develop:

  • Owners end up feeding large amounts of these grains to ‘satisfy’ those nutrient needs, and in the process potentially create more harm internally as a result, not just in the gut, but due to the fact that these nutrients are artificial and not in the natural form. Don’t forget about preservatives, dyes and other chemicals added to those grains!
  • Owners rely on these feeds, with synthetic nutrients, rather than relying on whole, real food. Nutrients from real food is entirely different than the synthetic form.  By relying on a processed feed, we are missing out on co-factors, macronutrients and phytochemicals that are present in real food that provide health benefits. So, many owners feed an expensive commercial feed, but then skimp on the quality of hay that they provide.

Simply put, a horse is not designed to consume a large amount of grains.  They were designed to consume forage for nutrient provisions and not rely on a processed grain to provide nutrition. I am not against grain use, as it is vital for energy production in the horse, but we have to consider the source and volume fed.  We do have to remember  that hay and pasture are also sources of carbohydrates, which can be used for energy.  Thus, when a high quality hay is fed at proper volumes, the need for excessive grain use becomes even less.

Through proper grain usage, ideally focusing on whole grains, along with proper hay and pasture provisions, I believe that many health and even lameness ailments can be better managed.  There is a connection between the many issues that we contend with in the horse and their diet.  The sooner we realize this, the faster we can make corrections to aid resolution.


Author:  Tom Schell, D.V.M., CVCH, CHN

Cur-OST Equine Health Products





2 thoughts on “Is My Horse’s Grain Creating Health Problems?”

  1. I understand whole oats are a whole food but my concern is still the carb load for easy keeper Friesians. Considering my horses get free choice hay with vitamins/minerals mixed with alfalfa pellets does it really benefit them to eat whole oats?

    1. Hi Kathy,

      The overall point regarding the article is to compare processed foods to whole foods, when it comes to grains. All foods will contain carbohydrates to some level or another. It is true that oats can be a high source of carbs and starches, but when fed in proper volumes, this is not a problem in most horses. I am certainly not advocating that a horse needs a grain in their diet, as this is not true. But those horses that are getting grains may be better served to move to a whole grain regimen. In terms of easy keepers, we have had many in our care over the years, and honestly, we have had them on whole grains, in specific amounts, mainly as a medium for proper supplementation. It is more a treat, and not a meal. Grains are not a meal. The horse should be acquiring almost all of their nutrition from whole foods, grains, hay and pasture, and not through supplementation of synthetics. Alfalfa pellets are okay in most cases, but again, we have to read the label and understand that an alfalfa pellet is not the same as alfalfa hay. It is processed on some level and thus, we will impact nutritional value. In some alfalfa pellet products, we also have additives, so we need to read the label. When it comes to easy keeper or metabolic patients, we need to further understand carbs and impact on health. There are ‘good’ carbs and ‘bad’ carbs. If we look at human research with type II diabetics, eating whole grains and fruits improves metabolic parameters and encourages weight loss. But, then we look at those foods and realize that they are ‘high’ in carbs. That tells us the difference between whole foods, good carbs, and processed ones with ‘bad’ carbs. So, are oats beneficial to an easy keeper? Sure, as they offer many health benefits, but again…everything in moderation. Thank you!

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