Is Corn the Culprit? The Truth About Cereal Grains in Horse Feed

General October 2nd, 2008

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by Beth Stelzleni of Mars Horscare US, Inc.

For many years, corn has had a bad reputation in the horse industry, and many horse owners today refuse to feed corn because they believe it is bad for their horses.  But is corn really a grain that needs to be avoided in horse feeds?    In order to really answer that question, it’s important that we understand a few basic principles about cereal grains in general.  The most common cereal grains we see included in horse feeds in the United States are corn, oats and barley.  These grains are included in horse feeds primarily to provide energy, but they are not created equal.  There are two main factors that affect the safety and performance of these grains in horse feeds: the starch found in the grains, and grain processing.  We’ll take a look at starch first.The starch found in cereal grains is what supplies energy to the horse.  Starch is an important component in horse feeds, but an excess of starch can lead to obesity, over excitability and metabolic problems.  Of the three cereal grains we mentioned earlier, oats have the lowest starch level of about forty to fort-five percent, barley has an intermediate starch level of about fifty to fifty-five percent, and corn has the highest starch level of about seventy to seventy-five percent.  If you’re just looking at starch levels, it’s easy to see why corn has such a bad reputation in horse feeds, as it is quite high in starch.  However, many of the problems that have occurred in horses fed corn are due to the amount that has been fed.  Corn is much more energy dense than oats.  This means that when looking at equal volumes of corn and oats, the corn will provide much more energy than the oats.  Many of the problems we see with horses on corn is due to the fact that these horses are fed a direct can-for-can substitution of corn for oats, which leads to an overfeeding situation.  When equal amounts of energy are fed, feeding corn does not bring any increased risks of obesity or making a horse hot than feeding oats or barley.

When looking at the starch in cereal grains, it’s important to also look at the form of starch in that particular grain.  The different starch structures play a huge role in the digestibility of starch.  We want the starch in our horses’ feed to be digested in the foregut of the horse – the portion of the horse’s digestive tract that includes the stomach and small intestine.  The general rule of thumb is that the more digestible the starch is, the safer it is for the horse (and the lower the risk of metabolic problems).  Oats have a form of starch that is readily digested in the horse’s foregut.  The starches found in corn and barley, however, are not readily digestible in the horse’s foregut and therefore have a higher risk of passing undigested into the horse’s hindgut where they could potentially cause problems.

Knowing that corn has a higher starch content than oats -and that corn starch is also less digestible, it might be easy to say that corn deserves it’s bad reputation.  Before we make that assumption though we need to consider one more factor: grain processing.  A few examples of processing methods include rolling, cracking or grinding, and these methods all exist to increase the digestibility of grains.  Studies have shown that processing of oats and barley does not make any substantial differences in the digestibility of starch.  However, when corn is ground or popped, the starch digestibility increases dramatically.  If we can pop corn, or cook it at high heat, we can increase the starch digestibility to about 90%, which would make corn an extremely safe grain to feed your horse.

As you can see, there are reasons that corn should be fed in moderation and with some caution, but it is not as terrible or dangerous as it’s reputation would have people believe.  As long as corn is fed in the correct amounts and is processed to aid in starch digestibility, it can actually be a nutritious, healthy addition to your horse feed.

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