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Healthy Horses = Healthy Hooves

 by Sally Hugg

Like a gleaming coat, healthy hooves are a reflection of a horse’s overall state of health and nutritional status. Common factors affecting the quality of the hoof are genetics, environment, correct trimming, and nutrition.  Optimal nutrition, based on the horse’s needs, is a key element in encouraging strong, healthy hooves.

Horses evolved as constant grazers of high fiber, low energy forage. Many health problems, such as colic and laminitis can be avoided by keeping the horse on a simple, mineral balanced grass hay diet. The equine digestive system is designed to break down fiber by means of microbial fermentation in the large intestine. Fiber can be a significant source of energy for the horse and many moderately worked horses can obtain all of their protein and energy needs from quality hay alone. Because some grass hays may contain surprisingly high levels of sugar, horses that are easy keepers or insulin resistant should be fed low sugar hay. Sugar and starch content can be tested by sending a sample to a forage testing laboratory such as Equi-analytical http://www.equi-analytical.com

Horses that work hard, such as endurance or race horses, will perform best with a higher carbohydrate diet, including grains. Carbohydrates from grains (starches) are digested by enzymes in the small intestine and converted into glucose for readily available energy. Grains need to be slowly introduced to the horse’s diet and fed in several small meals rather than all at once. Excess starch that passes from the small intestine to the large intestine may result in carbohydrate overload, which can result in colic or laminitis. When the horse’s workload is reduced for any reason, the grain portion of the diet needs to be reduced accordingly. For many moderately worked horses, beet pulp, a high energy fiber, can substitute for most or all of the grain.

Protein is required for growth and tissue repair. Protein requirements increase slightly with exercise, but the protein to calorie ratio does not. There are 22 different amino acids that are needed for protein synthesis, some of which can be synthesized by the body. There are 10 “essential amino acids” that must be supplied by the diet to the horse – lysine, methionine, arginine, histidine, isoleucine, leucine, phenylalanine, threonine, tryptophan, and valine. Lysine is commonly low in mature grass hay rations and must be supplemented, particularly for growing horses. Mature horses at maintenance are less sensitive to protein quality than growing horses, but protein needs should never be overlooked. According to the National Research Council guidelines, a mature horse needs approximately 23 - 30 grams of lysine daily for maintenance. Most grass hays only contain .3 - .6% lysine, however, a few pounds of alfalfa can supply the lysine needs of adult horses. Lysine may also be supplemented by adding other feeds, such as beet pulp, flax, rice bran and sunflower seeds. Methionine is another amino acid that is important for healthy hoof growth and, and like lysine, is usually deficient in grass hay diets. The actual requirements for methionine in the horse have not been established, but have been estimated to be roughly 25% of the levels for lysine.

A horse’s natural diet is low in fat. Most grass hays contain less than 3% fat. Horses do require certain essential fatty acids, however, and omega 3 and 6 are important for good health. Most horses get sufficient omega 6 in their regular diets, but unless they have access to green grass, omega 3 needs to be supplemented. Feeding 4 oz. daily of freshly ground flax seed will supply sufficient levels of omega 3 fatty acids. A 4 to 1 ratio of omega 3 and omega 6 seems to work well for most horses. Horses that are prone to allergies, such as sweet itch (caused by gnat bites) often respond well to the addition of ½ cup of ground flax seed to the daily diet.

Adding fat in the form of corn oil or other stabilized oils to a horse’s diet is a popular means of increasing calories without adding carbohydrates. These stabilized oils, however, do not supply omega 3 essential fatty acids. Processing oils to remain stable on a store shelf destroys fragile essential fatty acids, the same way exposure to light, heat and oxygen does. Fat provides calories, but it does not build, muscle, bone or connective tissue. While horses are able to digest and utilize high fat diets, it is best to avoid them for the serious athlete. High fat diets have been linked to insulin resistance in ponies and should be avoided in insulin resistant horses.

Minerals are involved in many bodily functions, such as formation of bone and connective tissue, hormones, metabolism and energy use. A proper balance of minerals is also important in hoof growth and quality.
Calcium and phosphorus and their ratio to each other are related to normal hoof development. Calcium is needed for laminar attachment in the hoof horn. Excess phosphorus can block the absorption of calcium from the small intestine. This can result in a calcium deficiency and cause weak and abnormal bones.

Magnesium is important for a properly functioning nervous system, metabolism, and energy regulation. Magnesium deficient diets can induce insulin resistance, while magnesium rich diets may prevent it. Magnesium deficiency and insulin resistance are also very commonly found in horses that are extremely "easy keepers", obese, with abnormal fat deposits like large crests or fat deposits at odd places on their bodies.  High calcium diets can interfere with absorption of magnesium. Ideally, aim for a 2:1:1 ratio of calcium to phosphorus and magnesium.
Trace minerals include iron, copper, zinc, manganese, cobalt, iodine and selenium. These minerals are referred to as “trace” because they are only needed in very small amounts by body, but they are still very important. Like calcium and phosphorus, trace minerals need to be in the correct ratios with each other, in addition to being present in the proper amounts. Too much of one can interfere with absorption of another. For instance, high levels of iron can compete for absorption of copper and zinc. High levels of zinc can cause a deficiency of copper.  A good ratio to aim for is 4:4:4:1 for iron, zinc and manganese to copper.

Some trace minerals, such as selenium have a fairly narrow margin of safety. The horse needs selenium for normal muscle function and normal function of the immune system. Toxicity is characterized by loss of appetite, loss of mane and tail hair, and in the severe form, blindness, loss of the hoof wall, paralysis, and death.

Excesses of iodine will produce the same symptom (goiter) as too little. Iodine is essential for the synthesis of thyroid hormones that regulate metabolism. Kelp is a very rich source of iodine and a horse regularly fed kelp based supplements may run the risk of iodine excess.
How do you know if your horse needs supplementation? Start with the greatest part of your horse’s diet – hay. Most full sized adult horses consume 15 – 25 lbs of hay per day. If you can, you should obtain an analysis of your hay and determine what is in it. You simply can’t tell by looking at it or going by what kind of hay it is. For instance, we know that alfalfa is usually high in protein and calcium compared to grass/cereal hays, but other nutrients can vary widely depending on soil and growing conditions. Since I started testing local hay in 2004, I have accumulated some interesting data on common deficiencies and excesses in west coast hay. A good source for data about hay is the Equi-Analytical Laboratories website http://www.equi-analytical.com/default.htm  

The most common finding in hay is high iron and very low copper and zinc. Excess iron is not beneficial for horses and can interfere with copper absorption, which is already in short supply. To make matters worse, feed companies often add more iron to their products. I have tested several brands of senior feeds and found that the iron levels were over twenty times higher than what they should have been according to NRC guidelines. Feed companies are not required to list iron levels on their tags, so a consumer has no way of knowing how much iron is in a product without the expense of sending a sample off to the lab. Sometimes you can ask a feed company how much iron is in their products and they will tell you how much they add, but that is not the same as the actual amount present in the feed.
Before you decide to shop for a supplement, read the National Research Council book, “Nutrient Requirement of Horses”. Understand what your horse does or doesn’t need. Many expensive products are full of ingredients that your horse might not need or benefit from. You can look up the NRC recommendations for your horse, according to age, weight and activity level, by going to the calculator at http://nrc88.nas.edu/nrh/

Listed below are the recommendations for a mature 1,100 lb. horse at maintenance.

  • Crude Protein   540 – 720 grams
  • Lysine                   23 – 31 grams
  • Calcium                         20 grams
  • Phosphorus                  14 grams
  • Magnesium                  7.5 grams
  • Potassium                    25 grams
  • Sodium                         10 grams
  • Chloride                        40 grams
  • Sulfur                            15 grams
  • Copper                           100 mg
  • Zinc                                400 mg
  • Iron                                400 mg
  • Manganese                    400 mg
  • Iodine                             3.5 mg
  • Selenium                            1 mg

The nutrient requirements for horses is based upon the National Research Council “Nutrient Requirements of Horses” sixth revised edition  (2007)