Minerals for your horse: striking the right balance

By Rex A. Ewing
Correspondent

Somewhere between the meat-and-potatoes subject of hay and grain, and the glitzy, fashionable topics of vitamins, glucosamine and MSM, lie the minerals--the nebulous, elemental necessities of life.

In a chemical sense, minerals are about as simple as it gets. There's nothing fancy about them. Just good, hard, submicroscopic chunks of the same stuff the earth is made of. But unless they are provided for your horse in the proper amounts and ratios, they just might pave the way to trouble.

There are two categories of minerals: the macrominerals--so called because they are needed in relatively large quantities--and trace minerals, which are required in small amounts of less than a gram per day.

We're all familiar with the macrominerals. They include the calcium, phosphorus and magnesium found in bones and teeth; the sulfur needed to hold proteins--and, by extension, your entire horse--together; and the potassium and salt (sodium chloride) which together regulate the osmotic pressure within living cells.

Trace minerals are considerably less conspicuous. Among them are zinc, an immune-system heavyweight and key component in hundreds of enzyme systems; copper, another enzyme contributor and, along with manganese, an essential element for the health and synthesis of joint and connective tissue; iodine, a critical component of thyroid hormones; iron and cobalt, both needed for the formation of hemoglobin; and selenium, a mineral necessary in minute quantities for the growth and maintenance of muscle tissue.

These are the main players. Some have relatively minor roles in a balanced feeding program since they are usually present in adequate amounts in grains and forages, while others need to be supplemented. Still others are occasionally found trying to hog the show, upsetting the delicate balance nature intended.

Which are the ones to watch out for?

Most macromineral-related problems in horses are caused by either too much calcium or too little salt. While all horsemen know the golden 2:1 calcium-to-phosphorus ratio they should aim for in their feeding programs, many are unclear in what feeds these minerals naturally occur. Here in North Forty country, alfalfa hay is the chief forage for a lot of horses, and so it should be; alfalfa is loaded with protein and other essential nutrients, making it a nutritious forage.

But, from a young horse's point of view, it might also be too rich in calcium, especially since calcium is also added to practically every grain mix and mineral supplement on the market. Without an adequate amount of phosphorus to restore balance, calcium can lead to serious problems in young horses. Epiphysitis, a pathological transformation of cartilage into bone, is a painful, crippling condition caused by a skewed calcium-to-phosphorus ratio. While too much of either mineral over the other can cause this disease, calcium is usually the one caught holding the smoking gun. Do your young ones have swollen fetlocks? Test your alfalfa and call your vet; if it comes up high in calcium, chances are he or she will tell you to feed some grass hay and add monosodium phosphate to the grain ration. It should turn things around.

Salt is an easier nutrient to get a handle on. Simply offer it free-choice; your horse knows how much he needs. Granular salt is preferable to block salt, especially for hard-working horses that may need 3 or 4 ounces per day. Iodized salt is the best, since it provides the trace mineral iodine, which will preclude the possibility of goiter.

What about trace minerals? If your local feed mill proprietor told you that you could only supplement one trace mineral, which one would it be? Personally, I'd opt for zinc. It's lacking in practically every grain and forage, yet it's so important there's not much that goes on inside, or outside, a horse without it. Besides its immune-system functions, zinc is needed for healthy hooves, hair and prostate.

After zinc comes manganese and copper. Both are a little low in most forages and grains. This is not likely to be a problem for maintenance horses or dry mares in early pregnancy, but for growing horses and performance horses, a little extra in the feed helps to assure strong, healthy joints. Fortunately, most feed mills include zinc, manganese and copper in their sweet-feed formulas.

Which trace mineral is the most troublesome? For working horses, iron probably tops the list. This is because there is a myth prevalent in the performance-horse community that large amounts of supplemental iron will improve a horse's ability to utilize oxygen. The truth is, as a component of blood, iron is well conserved in the body, and there are usually adequate amounts of iron in almost all grains and forages.

Too much iron--as from liberal doses of iron "tonics"--interferes with copper and zinc absorption, and slows the metabolism of phosphorus. These are all nutrients you want in your feed. To make matters worse, iron is a key nutrient for a host of pathological bacteria, nasty little critters you really don't want to encourage.

When it comes to minerals for your horse, there are lots of ways to cause a nutritional wreck, but with a little knowledge and common sense, most problems can be easily avoided. By knowing what's in your feed (Read that label!) and what your horse requires at each stage in his life, most, if not all, potential problems can be avoided before they begin.

It leaves you time to enjoy your horse, rather than wondering what's wrong with him.

Rex Ewing, author of "Beyond the Hay Days: Refreshingly Simple Horse Nutrition," and former president of the John Ewing Co. (a horse supplement manufacturer) lives in Buckhorn Canyon, west of Fort Collins. He can be reached at rex@pixyjackpress.com. Autographed copies of his book can be ordered at www.pixyjackpress.com or by calling 970-215-5068.