Nutrition and Feed Management
The primary objective of a feed management program is to supply your horses with a diet consisting of grass and hay (forage) and cereal grains, usually in the form of a commercial concentrated feed (concentrates), which provides each horse with the necessary fuel to perform their jobs. A horse in “optimal condition” has energy appropriate for their level of activity, a shiny coat and healthy hooves, while remaining free of disease. An “optimal feeding program” accomplishes these goals at the cheapest cost. Horses require six nutrients to stay healthy: water, protein, carbohydrates, fat, vitamins and minerals. While free access to clean drinking water is essential for all horses, the levels of the remaining nutrients vary according to geographic location and what types of activities each individual engage in.
The horse’s body is composed of fifty to eighty percent water (Brown and Powell-Smith, 1994). Water is vitally important for regulating body temperature, excreting wastes, carrying and absorbing other nutrients throughout the body, and providing a base for all bodily fluids. Horses drink at least six gallons of water a day; that amount increases if the horse is performing heavy work (i.e. racing) or supporting a nursing foal.
Protein, made of amino acids, is the “building block” of tissue and is responsible for growth and repair of the body (Marconi, 2002). The amount of protein needed in a horse’s diet varies widely, depending on age and activity; a young, growing horse requires the most protein. While protein can be a source of energy for horses if fed in excess, it is the most expensive nutrient to provide. Additional energy can be supplemented in other, less expensive ways. Commercial feeds are sold by the level of protein content, anywhere from ten percent to sixteen percent. This usually provides the horse with all needed amino acids. However, close attention must be paid to the feed label, as lysine is commonly deficient. This can be supplemented most efficiently with a lysine rich soybean meal.
Carbohydrates supply the main source of energy in a horse’s diet. Simple carbohydrates include starch, glycogen and sugars (Brown and Powell-Smith, 1994). The bulk of simple carbohydrates is digested in the small intestines and transported throughout the body in the form of sugar. High levels of glucose, a simple sugar, can be found in young plants; starches are found mostly in cereal grains. Excess glycogen is converted to fat so it can be indefinitely stored in the fatty tissues of the body. Complex carbohydrates include cellulose and lignin, and are found in forage (Brown and Powell-Smith, 1994). Cellulose, a fiber found in plants, is digested by bacteria in the horse’s cecum and converted to glucose. It is then either used as energy or stored as fat. Although horses are incapable of digesting lignin, it is a vital source of fiber, aiding digestion and excretion.
Fat forms a protective layer around organs, keeps the horse warm, and produces a sleek, shiny coat. A natural diet of forage can provide up to three percent fat, although a concentrated diet containing twenty percent fat is common and safe (Marconi, 2002). Fat contains over twice as much energy as carbohydrates but its high digestibility yields the least amount of internal body heat (Brown and Powell-Smith, 1994). This makes fat a safe medium in which to supplement extra calories to working horses. Cooking oils, most often corn oil, are commonly added to the feeds of thin horses to safely improve condition and health.
Vitamin deficiencies are hard to find among horse diets. Green pasture, quality hay and sunlight provide nearly all vitamins needed by the horse, although the vitamin content of hay decreases when the bales are stored for longer than six months. Vitamin deficiencies in forage are easily made up by concentrated feeds. Biotin is a vitamin supplement that improves the condition of brittle, weak hooves. Although there is little scientific evidence to support this phenomenon, anecdotal evidence from horse owners and farriers supports the use of this supplemental vitamin (Marconi, 2002).
Adequate mineral levels are necessary for most chemical reactions in the body to occur. Centuries of intense agriculture have drained the soil mineral levels of many geographic regions (Brown and Powell-Smith, 1994). However, minerals are easily replaced in the equine diet by the addition of a “trace mineral salt block”. A salt block should be available to the horse at all times, either in the stall or out on pasture. The ration between two minerals, calcium and phosphorus, should be carefully monitored, especially with growing foals. There should never be more phosphorus than calcium in the diet; the ratio should fall between 1:1 – 3:1, although growing foals can have up to six times more calcium than phosphorus (Marconi, 2002).
The first step in designing a feed management program is determining which of feed classification each particular horse falls under (Marconi, 2002). The “maintenance” horse performs only light work each day, which may be done walking the pasture. Maintenance horses require very little other than good quality pasture and grass hay. Cereal grains may be given in addition to forage on an individual basis if the horse has difficulty maintaining optimal condition. “Working” horses require slightly more energy, in the form of protein and carbohydrates than horses merely walking a pasture; they generally require a concentrated feed. A mare in the “gestation” class requires little more than a maintenance horse until the third trimester of the eleven month pregnancy. In the early months of gestation, a mare can be kept on quality pasture and hay. As the ninth month approaches, the mare is generally given more protein and carbohydrates through concentrates. The last two classifications, “lactation” and “growth”, have the greatest nutritional demands of all horses. “Immediately after foaling, a mare’s energy requirements increase by as much as ninety percent, while protein requirements increase by fifty percent” (Mowrey, 1999). The first thirty days of lactation cause the mare to expend the most protein and carbohydrate energy and fat of any other period; the mare will need a rich diet to keep her and her foal healthy. For purposes of a feeding program, the foal will enter the “growth” classification at thirty days of age. The “growth” stage requires the highest protein diet and careful monitoring of minerals to ensure proper bone development.
Once the diet needs have been determined, the next step is to determine which types of forage and concentrates to feed (Marconi, 2002). A horse eats one percent to three percent of its body weight daily, more or less depending on the feed classification. Of that percentage, at least half should be in the form of grass and hay. For example, a horse weighing 1,000 pounds should receive at least fifteen pounds of forage each day and no more than fifteen pounds of concentrates. The type of forage and cereal grains given depends on the cost and quality of available feeds and the dietary needs of each individual horse.
There are two forms of hay, dried grasses and legumes. Hay is available in forty to ninety pound “square bales” (Figure 4.14) which is fed in “flakes” taken from the end of the bale. The convenient square bales are the preferred choice for stabled horses. “Round bales” (Figure 4.15) are much larger, weighing hundreds of pounds each. A round bale is rolled into a pasture and is often contained in a round feeder that allows six to eight horses to feed at a time. Round bales are more economical and convenient for pasture-kept horses. County extension agents and select feed stores can perform a nutritional analysis of a sample taken from the core of a hay bale. A careful inspection of the stem to leaf ratio, color (greener hay usually contains more nutrients), presence of weeds, smell, mold or dust content and moisture level (determined by weight) is often as informative as a nutritional analysis. Hay must be cured and stored properly to avoid spontaneous combustion. If the moisture content of the hay was too high when it was baled, it will cure at very high temperatures. Moist, warm hay kept in a poorly ventilated barn loft or stall is at high risk of bursting into flames. Only small amounts of hay -one day’s worth- should be kept in a barn housing horses. The rest of the bales should be kept in a separate facility.
Figure 4.14 -Square Bale
Figure 4.15 -Round Bales
Grass hay is extremely high in fiber and tends to have a protein content between eight and ten percent (Marconi, 2002). Timothy (Figure 4.16) is a grass grown primarily for hay, but is sometimes incorporated into pastures. It produces well in early spring and grows under a wide range of soil and climatic conditions (Heusner, et al, 1999). Orchardgrass (Figure 4.17) is fast growing and more heat tolerant than timothy, although it cannot stand close-grazing (Heusner, et al, 1999). This makes it less suitable for pastures. Kentucky bluegrass is grown throughout the United States, but is not utilized in the western states. Bluegrass is an extremely nutritious and resilient pasture grass, but lacks these qualities as dried hay. Fescue is a hardy plant that is gaining popularity across the country as a pasture grass. However, fescue must be used with caution, as pregnant mares turned out on fescue pasture can develop “fescue toxicosis” requiring expensive medication. Fescue toxicosis often results in abortion of the foal. Timothy and orchardgrass are the most commonly fed grass hays in the Ohio region.
Figure 4.16 -Timothy Grass
Figure 4.17 -Orchardgrass
Legumes have more calories, protein and calcium than grass hay (Marconi, 2002). A protein level between fifteen percent and eighteen percent is common among legumes, which makes it a good choice for pregnant or lactating mares. Alfalfa (Figure 4.18) is the most commonly fed legume, being used in pastures and as dried hay. However, the potential for blister beetle contamination is greatly increased in alfalfa. Horses poisoned with cantharidin, the toxic material produced by the half-inch long beetles, typically die two days after blisters appear inside the mouth and digestive tract (Heusner, et al, 1999). Red clover is a highly palatable legume that is nutritionally similar to alfalfa. However, red clover is more difficult to cure properly, which causes many horse people to avoid feeding it. Clover also causes horses to slobber profusely. Although the slobbering is harmless, slobbery horses are undesirable for most activities.
Figure 4.18 -Alfalfa
Cereal grains are most often fed in the form of a commercial feed. Although many people prefer to blend their own grain mixes, commercial concentrates are more economical and convenient. Commercial feeds also guarantee a balanced ration, providing the horse with all essential nutrients that may be missed in a personally mixed feed. Feed labels, regulated by The American Association of Feed Control Officials, offer a guaranteed analysis of nutrients, an ingredient list and feeding instructions. Commercial feeds are available as complete feeds, meant to supply all the cereal grain and forage needs of a horse, or as grain mixes meant to be fed along with grass or legume hay. There are numerous types of commercial feeds available for purchase, from the easily recognizable form of corn, oat and molasses, to pellets made from ground grains. Commercial concentrates are typically priced between $0.12 and $0.17 per pound, depending on protein level. The price of hay also depends on the protein level. Square bales cost between $2.00 (grass) and $5.00 (legume) whereas larger round bales are sold for between $12.00 and $25.00 each.
 The rest of the sections in this chapter are based on notes taken during a field study in Lexington, KY in the spring of 2002 and personal experiences from the past ten years of horse ownership. The notes are available for review upon request.