How Important is Protein in Your Horse's Diet

by Karen E. Davison, Ph.D., Land O’Lakes Purina Feed Manager-Equine Tech. Services

Most horse owners have, at some time, purchased their horse feed primarily based on the protein content of that feed. “I need a good 14% sweet feed.” or “What do you have in a 12% horse feed.” or even, “How much is your 14% calf creep feed? I’m not paying extra for the same thing just because there’s a horse on the bag.”; these are statements most feed store owners have heard. One reason for the focus on protein is because it is an important part of a horse’s diet, but also because the percent protein is one of the few pieces of information stated on the feed tag. Also, some products are named just by the percent protein; “Super Horse Feed 10”, “Super Horse Feed 12”, etc. This focus on percent protein in a feed presents a couple problems for the horse.

First, you might be surprised to learn that horses don’t actually have a dietary protein requirement. Instead, they have an amino acid requirement. Amino acids are the building blocks for protein. When you consider that all tissues in the body have a protein component, you might wonder what makes those tissues different. What makes muscle different from skin or hair, when all are made largely of protein? The difference is in the amino acid content of the proteins in that tissue. Amino acids are strung together to build proteins and the order in which they are connected determines which protein is made. Of the 22 known amino acids making up proteins in the animal body, 8 are classified as essential (cannot be manufactured by the body and must be supplied in the diet) and 14 as non-essential (can be manufactured by the body with proper nutrition). The purpose of protein in the diet is to supply the amino acids needed for tissue growth, repair and maintenance. Not all dietary protein sources supply the proper balance of amino acids to the horse.

For example, cottonseed meal and soybean meal are both ingredients used to supply protein in feed products. Both ingredients will contain around 40 – 45% protein, however, soybean meal has a better amino acid balance for horses than cottonseed meal. If you feed two groups of foals different diets containing the same protein level but one diet has soybean meal and the other is made with cottonseed meal, the youngsters eating soybean meal will grow better than those eating cottonseed meal. Both groups consume the same amount of total protein, but the foals on cottonseed meal are deficient in lysine, one of the essential amino acids.

When you look at the scenario of using a calf creep feed instead of a horse feed, you must understand that cattle can utilize protein sources like cottonseed meal to meet their amino acid requirements. Their digestive systems allow them to make use of lesser quality protein sources. So, what might be a very good calf creep feed would be a very marginal growing horse diet.

Second, the percent protein in the feed doesn’t give the whole picture of how much protein that diet supplies to the horse. For instance, if a horse is eating 10 lbs of oats which are 11.5% protein, he is getting 1.15 lbs of protein from those oats (10 lbs X 0.115 = 1.15 lbs). If that horse’s owner decides to change to Omolene 200 which is 14% protein, you’d think the horse would be getting more protein, right? Well, because Omolene 200 has about 30% more calories per pound than oats, you’d only need to feed 7 lbs of Omolene 200 to keep the horse in the same body condition. That would supply 0.98 lbs of protein (7 lbs X 0.14 = 0.98 lbs). You’d actually provide less protein feeding the higher protein feed, but the amino acid balance provided by the Omolene 200 would be more beneficial to the horse.

Protein is a major component of the body. Not only in building cells and repairing tissues, but proteins also form antibodies to combat invading bacteria and viruses; they make up enzymes and some hormones; they build nucleoproteins such as DNA; they carry oxygen throughout the body and participate in muscle activity. Without the proper balance of amino acids in the diet to support all these functions, body systems begin to decline. The amino acid balance in the diet will be reflected in a horse’s hair coat, hoof quality, muscle tone and overall health and bloom. So, when you make a decision on which product to feed your horse, consider the amount of protein, but also take into account the amount of feed you will need to provide each day along with the quality of the protein sources used in that feed.

For more information on Purina Horse Feeds, or to find the dealer nearest you, visit http://horse.purinamills.com or call (800)227-8941.