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Basics of Horse Nutrition

Several breeds and types of horses are used in a wide variety of activities throughout Pennsylvania and surrounding states. The majority of these horses are owned and managed for recreation or sport and not for profit by the owners. One of the greatest expenses in owning horses is feed. Feed costs can be minimized by keeping the horse healthy and by feeding a balanced ration that meets the horses nutritional needs.

More myths are associated with feeding horses than with feeding most other animals. This is in part due to the lack of current nutritional research information as well as an increasing number of horse owners who are unfamiliar with the basics of horse nutrition. Nutritional needs will vary considerably among horses depending on individual age, weight, and level of activity. There are no magic supplements, high performance feed "secrets", or short cuts that will transform any horse into a champion.

Horses naturally use forages as a primary component of their diets. Adequate forages are a basic necessity for normal functioning of the horses digestive system. This requirement for forages is most easily supplied by pasture and hay.

Mature horses will generally consume 2 to 2.5 percent of their body weight in feed each day. For example, a 1,000 pound horse should consume approximately 20 to 25 pounds (90 percent dry matter) of feed per day. The anatomy of the horse's digestive tract restricts effective digestion and utilization of low quality forages that are high in fiber. The poor digestion of low-quality forages can restrict the amount of dry matter that a horse can eat to a level below what is necessary to meet the horses nutrient needs. Therefore a premium should be placed on using high-quality forages in the horse's diet.

Ideally, horses should consume a minimum of 1 percent of their body weight in hay or pastures each day. Mature horses performing minimal or no work can be maintained on high quality forages without supplementing their diet with grain. However, growing, breeding, or working horses require supplementing the forage with a grain or concentrate to meet their additional nutrient requirements. As a general rule, forages should supply one half or more of the total weight of the feed consumed daily for optimum horse growth and development.

Forages can provide varying amounts of the nutrient requirements depending on the forage quality and amount consumed. The nutrient content of the forage and concentrate in the horse's diet must be known to properly balance the diet. Once the quality of the feeds are known, then proper amounts of each can be calculated to meet the nutrient requirements.


Pasture for Horses

High-quality, properly-fenced pasture represents one of the best and least expensive sources of summer feed for a horse. In addition, a well kept pasture can provide the most natural and healthy environment for exercise and rest.

Productive, well-managed pastures can provide most of the feed requirements of horses at the lowest cost. In fact, good pasture alone is sufficient to meet all of the nutritional requirements for many classes of horses. Yet, poorly-managed pastures supply little or no feed, and are frequently the source of many internal parasites.

General guidelines for the pasture needs (if the pasture is to serve as a feed source) for horses which have a mature weight of 1000 to 1200 lbs. are:

When acreage is very limited (less than one acre per horse), exercise may be the main use of the pasture. Pasture for this purpose will not supply more than a minimum amount of feed. However, with limited pasture pasture acreage, rotational grazing systems are the most effective method to maximize forage production and consumption. In this system, a group of compatible horses can graze a paddock (area of divided pasture) for approximately 3 to 6 days and then be moved (rotated) to a fresh paddock. Well limed and fertilized Kentucky bluegrass should be the main grass for this type of area. Kentucky bluegrass withstands close and continuous grazing better than most other grasses and when well established and properly fertilized, it produces a reasonably dense and attractive sod.


Pasture Improvement

If you already have good stands of desirable grass and legume species, proper soil fertility combined with good management will be sufficient to assure good horse pasture. Most permanent bluegrass pastures produce less than 2000 pounds of dry matter per acre per year which is far below their potential. Yields on many pastures can be doubled simply by applying lime and fertilizer. Liming and topdressing Kentucky bluegrass pastures with phosphate, potash and nitrogen costs much less and is less work than complete pasture renovation. Furthermore, it is often possible to have these materials custom applied at a relatively low cost.

Apply lime and fertilizer according to soil test results and recommendations. A soil test will determine the pH (acidity) and nutrient level of your soil. Soil testing kits and information on how to take samples are available through your local extension agricultural agent. The response is often slow when you apply lime and fertilizer on the surface of established pastures. It may take 1 to 3 years, depending largely on the lime needs and species present in the pasture, before your pasture sod is thick and productive again.

If you don't have a good stand of desirable species, you may want to renovate the pasture by destroying the existing plants and planting productive mixtures. This procedure usually results in the highest yield increase per acre, but will also be relatively expensive to complete. If you plan to renovate an old pasture you should consider the following points:

  1. Soil test for lime and fertilizer requirements. This is the only sure way of knowing how much lime and fertilizer are needed.
  2. Apply required lime several months before the actual seeding. Disking or plowing will help to mix the lime evenly throughout the soil.
  3. Select a seed mixture that complements the pasture drainage characteristics.
  4. Destroy or suppress the old pasture by plowing or use of herbicides.
  5. Use the appropriate method of seeding based on extent of tillage.
  6. Protect the seeded area until the new plants are well established. Where recommended mixtures are seeded without a companion crop and weeds are controlled, new seedings can become established in a single year.

In heavy traffic areas, along fences and around gates and water troughs, tall fescue may be used. While it is generally considered less palatable than bluegrass, tall fescue produces one of the toughest and heavy traffic sods of any adapted grass. Older stands of fescue often are infested with an endophyte (within the plant) fungus. Toxins associated with this fungus can cause lowered reproductive rates, abortion, agalactia (lack of milk) and prolonged gestation with mares. Use endophyte-free tall fescue seed whenever establishing new fescue stands for horses. Brood mares should be removed from pastures containing endophyte infested tall fescue at least 90 days prior to foaling.


Pasture Management

Whether you improve your pastures by the use of lime and fertilizer or by reseeding, sound management is essential to keep the desired species persistent and productive.

Avoid over or under grazing. Horses are notorious spot grazers. They will seriously damage desired species in some areas unless they are moved into new pastures frequently. Therefore, some form of rotational grazing is desirable. The correct acreage per horse changes with the season as well as with other factors. However, a good rule is to provide at least one acre of good quality pasture per horse. Then set up 5 or 6 paddocks, letting the horses graze first in one area for about one week and then change to another. This system helps to keep the legumes and grasses growing better and increases the feed available per acre. In addition, by rotating the horses from pasture to pasture you can break the life cycle of some parasites.

Clip pastures regularly during the growing season. Clipping at a height of 2 to 3 inches after horses are moved to a new paddock helps to control weeds, prevent grasses from heading and in general keeps the pasture in a more desirable condition.

Drag pastures with a chain link harrow at least once per year. Dragging helps to spread manure droppings which reduces the parasite populations by exposing them to air and sunlight. Dragging also helps to smooth over areas dug up by horses' hoofs on wet soil.

Apply fertilizer as needed. Improved horse pastures must be fertilized annually if legumes and grasses are to persist and remain productive. The fertilizer to use depends on the pasture species present. A complete soil test every 2 or 3 years is your best guide.


Hay for Horses

High quality hay can provide most of the nutrients needed for a mature horse. High quality hay is cut early and is leafy, green in color, and is free of must, mold, dust, and foreign material such as weeds and stubble. This type of hay is usually rich in energy, protein, minerals and vitamins, and is readily consumed by horses.

In the past, there has been a belief that horses should not be fed a legume hay because it would cause digestive disorders. Grass hay, especially timothy has been the preferred hay. However, research has dispelled the notion that legumes do not make good hay for horses.

Straight legume hay or legume-grass mixed hay are highly acceptable when they are cut early, leafy and free of molds or other dusts. Respiratory or digestive disturbances frequently associated with feeding hay are more related to dust and mold than to mixtures. In general, well managed legume-grass hays are higher in protein and minerals than straight grasses under similar management. However, protein and mineral levels are readily changed by time of cutting and other hay-making practices. With good management most hay species or mixtures can be satisfactory for horses. Alfalfa hay, while normally high in protein, may contain an excessive amount of calcium in relationship to phosphorus (wide Ca:P ratio) when fed as the sole source of forage to young, growing horses.

To be sure of the nutritive quality of the hay which is being fed, have it analyzed. For more information on testing the quality of forages check with your local county agricultural extension agent.


Hay Production Tips

If you plan to buy hay for your horse, then consider the factors discussed above. However, if you plan to grow and harvest your own hay, follow the steps listed below. They will help you to consistently produce high yields of high quality hay.

  1. Choose adapted species, varieties and mixtures. In general, simple mixtures consisting of a single legume such as alfalfa and a single grass such as timothy are preferred over straight legume or straight grass seedings. The Penn State Agronomy Guide is an excellent source of information on species and mixture selection. It is available through your county extension office.
  2. Fertilize annually. A complete soil test provides the best guide for proper fertilization. Where soil test information is not available, topdress legume-grass stands annually with a minimum of 50 pounds of phosphate and 150 lbs. of potash (example 500 pounds of 0-10-30 or equivalent) per acre. If your hay field contains less than a 30% stand of legumes you can increase yield by applying 60 pounds of nitrogen per acre in late winter or early spring.
  3. Harvest on time. To assure high quality feed, and at the same time keep stands productive and persistent, harvest hay crops at the proper maturity stages.
  4. Plan hay making operations to save leaves. The plant leaves are higher in digestibility and feed value, including protein and minerals than any other plant parts. Hay that has been cut early and conditioned will normally contain more leaves and dry much faster than non- conditioned hay. It also tends to be softer and more readily accepted by animals. Other field operations such as raking should be carried out at high enough moisture levels to minimize leaf loss.
  5. Dry and store to prevent dusts and molds. As indicated previously, dusty and moldy hay is unacceptable for horses. Conventional field dried hay must be 20 percent moisture or less for safe storage. Of all perennial species grown for hay in Pennsylvania, red clover is one of the most difficult to field cure.

Today a number of chemical preservatives are being marketed which if properly applied at the time of baling make it possible to bale and store hay safely at moistures up to 25 percent. Research indicates that hay treated with most chemical preservatives is safe to feed to horses as long as no dust or mold is present.


Health Concerns when Feeding Forages to Horses

Horses are extremely susceptible to molds, fungi, and other sources of toxic substances in forage. Mold problems generally occur in hay that has been baled at too high a moisture level (20% or more) without the use of a preservative. This is especially a problem with first cutting hay because it is harvested during a period of time when it rains frequently and the weather conditions are less than ideal for hay drying.

Always use clean, unmoldy forages when feeding horses. In addition to molds and fungi, some forage species contain chemical compounds that can have negative health effects on horses.

Another health problem could occur when horses are fed hay that contains blister beetles. When consumed, the beetle causes irritation to the lining of the digestive tract which usually results in death. Alfalfa hay that has been produced in southern areas of the U.S. is most generally associated with the potential to contain blister beetles. Do not feed any hay containing blister beetles to horses! Poisonous plants in pastures or hay can be fatal to horses. Ornamental shrubs and nightshade are the most common poisonous plants in Pennsylvania. However, any plant that is known to be poisonous to other animals is probably poisonous to horses. Some poisonous plants are highly palatable and should be identified and removed from pastures. However, many poisonous plants are not palatable and horses will not eat them unless there is inadequate forage available to meet their needs.


Black Walnut Toxicity

Horses may be affected by black walnut chips or sawdust when they are used for bedding material. Close association with walnut trees while pollen is being shed (typically in May) also produce allergic symptoms in both horses and humans. The juglone toxin occurs in the leaves, bark and wood of walnut, but these contain lower concentrations than in the roots. Juglone is poorly soluble in water and does not move very far in the soil.


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This page was last updated on December 09, 2007