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Equine nutrition is the feeding of , pony, , , and other equines. Correct and balanced nutrition is a critical component of proper horse care.
Horses are non-ruminant herbivores of a type known as a "hindgut fermenter." Horses have only one stomach, as do humans. However, unlike humans, they also need to digest plant fiber (largely cellulose) that comes from grass or hay. like cattle are foregut fermenters, and digest fiber in plant matter by use of a multi-chambered stomach, whereas horses use microbial fermentation in a part of the digestive system known as the cecum (or caecum) to break down the cellulose.
In practical terms, horses prefer to eat small amounts of food steadily throughout the day, as they do in nature when grazing on pasture lands. "Horse Nutrition - Frequency." Bulletin 762-00, Ohio State University. Web site accessed February 9, 2007. Although this is not always possible with modern stabling practices and human schedules that favor feeding horses twice a day, it is important to remember the underlying biology of the animal when determining what to feed, how often, and in what quantities.
The digestive system of the horse is somewhat delicate. Horses are unable to regurgitate food, except from the esophagus. Thus, if they overeat or eat something poisonous, vomiting is not an option. (1998). 9780876056066, Howell Book House. ISBN 9780876056066 They also have a long, complex large intestine and a balance of beneficial microbes in their cecum that can be upset by rapid changes in feed. Because of these factors, they are very susceptible to horse colic, which is a leading cause of death in horses. Therefore, horses require clean, high-quality feed, provided at regular intervals, plus water or they may become ill if subjected to abrupt changes in their diets. March, Linda. "Feeding Your Horse To Avoid Problems," from University of Illinois, College of Veterinary Medicine. Web site accessed February 16, 2007 Horses are also sensitive to molds and toxins. For this reason, they must never be fed contaminated fermentable materials such as lawn clippings. Fermented silage or "haylage" is fed to horses in some places; however, contamination or failure of the fermentation process that allows any mold or spoilage may be toxic. "Horse Nutrition - Carbohydrates and fats." Bulletin 762-00, Ohio State University. Web site accessed February 9, 2007.
The esophagus carries food to the stomach. The esophagus enters the stomach at an acute angle, creating a one-way valve, with a powerful sphincter mechanism at the gastroesophageal junction, which is why horses cannot vomit.
The small intestine is long and holds to . This is the major digestive organ where 50 to 70 percent of all nutrients are absorbed into the bloodstream. "Horse Nutrition - The Horse's Digestive System." Bulletin 762-00, Ohio State University. Web site accessed February 9, 2007. Bile from the liver acts here, combined with from the pancreas and small intestine itself. Equids do not have a gall bladder, so bile flows constantly, an adaptation to a slow but steady supply of food, and another reason for providing fodder to horses in several small feedings.
The large colon, small colon, and rectum make up the remainder of the large intestine. The large colon is long and holds up to of semi-liquid matter. Its main purpose is to absorb carbohydrates which were broken down from cellulose in the cecum. Due to its many twists and turns, it is a common place for a type of horse colic called an impaction. The small colon is also long, holds about , is the area where the majority of water is absorbed, and where fecal balls are formed. The rectum is about one foot long, and acts as a holding chamber for waste, which is then expelled from the body via the anus.
An average horse drinks of water per day, more in hot weather, when eating dry forage such as hay, or when consuming high levels of salt, potassium, and magnesium. Horses drink less water in cool weather or when on lush pasture, which has a higher water content. When under hard work, or if a mare is lactating, water requirements may be as much as four times greater than normal. "Horse Nutrition - Diet Factors - Water." Bulletin 762-00, Ohio State University. Web site accessed February 9, 2007. In the winter, snow is not a sufficient source of water for horses. Though they need a great deal of water, horses spend very little time drinking; usually 1–8 minutes a day, spread out in 2-8 episodes.
Water plays an important part in digestion. The forages and grains horses eat are mixed with saliva in the mouth to make a moist bolus that can be easily swallowed. Therefore, horses produce up to or 85 lb. of saliva per day.
Fat exists in low levels in plants and can be added to increase the energy density of the diet. Fat has per kilogram of energy, which is 2.25 times that of any carbohydrate source. Mowrey, Robert A. "Horse Feeding Management - High-Fat Diets for Horses". from North Carolina Cooperative Extension Center , web site accessed February 14, 2007 Because equids have no gall bladder to store large quantities of bile, which flows continuously from the liver directly into the small intestine, fat, though a necessary nutrient, is difficult for them to digest and utilize in large quantities. "Digestive System 2" , web site accessed August 15, 2011 However, they are able to digest a greater amount of fat than can cattle. Horses benefit from up to 8% fat in their diets, but more does not always provide a visible benefit. Horses can only have 15-20% fat in their diet without the risk of developing diarrhea.
Carbohydrates, the main energy source in most rations, are usually fed in the form of hay, grass, and grain. Soluble carbohydrates such as and are readily broken down to glucose in the small intestine and absorbed. Insoluble carbohydrates, such as fiber (cellulose), are not digested by the horse's own enzymes, but are fermented by microbes in the cecum and large colon to break down and release their energy sources, volatile .
Soluble carbohydrates are found in nearly every feed source; maize has the highest amount, then barley and oats. normally have only 6-8% soluble carbohydrate, but under certain conditions can have up to 30%. Sudden ingestion of large amounts of starch or high sugar feeds can cause at the least an indigestion horse colic, and at the worst potentially fatal colitis or laminitis.
Protein is used in all parts of the body, especially muscle, blood, , horse hoof, and hair cells. The main building blocks of protein are . Alfalfa and other legumes in hay are good sources of protein that can be easily added to the diet. Most adult horses only require 8-10% protein in their diet; however, higher protein is important for lactating mares and young growing .
Minerals are required for maintenance and function of the skeleton, , and muscles. These include calcium, phosphorus, sodium, potassium, and chloride, and are commonly found in most good-quality feeds. Horses also need such as magnesium, selenium, copper, zinc, and iodine. Normally, if adult animals at maintenance levels are consuming fresh hay or are on pasture, they will receive adequate amounts of minerals in their diet, with the exception of sodium chloride (salt), which needs to be provided, preferably free choice. "Horse Nutrition - Minerals." Bulletin 762-00, Ohio State University. Web site accessed February 14, 2007. Some pastures are deficient in certain trace minerals, including selenium, zinc, and copper,Harper, Frederick. Spring Pasture for your Horses (AS-H 147), University of Tennessee Extension Service. Web page accessed July 4, 2009. see also, e.g. Frederick, Howard. "Selenium Deficiency" AzVDL Newsletter, Vol. 2, number 2, June, 1997. Page accessed July 25, 2008
Harper, Frederick and Bruce Gill. "Minerals for Horses, Part II: Trace Minerals" (PDF) Horse Express, Vol. 25, No. 1 January, February, March 2006, page accessed July 4, 2009. and in such situations, health problems, including deficiency diseases, may occur if horses' trace mineral intake is not properly supplemented.Watts, Kathryn, "Horse Mineral deficiency can create health problems" Rocky Mountain Research & Consulting, Inc., web page accessed August 15, 2011.
Calcium and phosphorus are needed in a specific ratio of between 1:1 and 2:1. Adult horses can tolerate up to a 5:1 ratio, foals no more than 3:1. A total ration with a higher ratio of phosphorus than calcium is to be avoided. Over time, imbalance will ultimately lead to a number of possible bone-related problems such as secondary hyperparathyroidism. (2025). 9780643065987, Landlinks Press. ISBN 9780643065987
and young growing horses through their first three to four years have special nutritional needs and require feeds that are balanced with a proper calcium:phosphorus ratio and other trace minerals. A number of skeleton problems may occur in young animals with an unbalanced diet. Hard work increases the need for minerals; sweating depletes sodium, potassium, and chloride from the horse's system. Therefore, supplementation with may be required for horses in intense training, especially in hot weather.
Solid feeds are placed into three categories: forages (such as hay and grass), concentrates (including grain or pelleted rations), and supplements (such as prepared vitamin or mineral pellets). Equine nutritionists recommend that 50% or more of the animal's diet by weight should be . If a horse is working hard and requires more energy, the use of grain is increased and the percentage of forage decreased so that the horse obtains the energy content it needs for the work it is performing. However, forage amount should never go below 1% of the horse's body weight per day.
Legumes such as clover or alfalfa are usually higher in protein, calcium, and energy than grasses. However, they require warm weather and good soil to produce the best nutrients. Legume hays are generally higher in protein than the grass hays. They are also higher in minerals, particularly calcium, but have an incorrect ratio of calcium to phosphorus. Because they are high in protein, they are very desirable for growing horses or those subjected to very hard work, but the calcium:phosphorus ratio must be balanced by other feeds to prevent bone abnormalities.
Hay is a dried mixture of and . It is cut in the field and then dried and baler for storage. Hay is most nutritious when it is cut early on, before the seed heads are fully mature and before the stems of the plants become tough and thick. Hay that is very green can be a good indicator of the amount of nutrients in the hay; however, color is not the sole indicator of quality—smell and texture are also important. "Horse Nutrition - Hay quality." Bulletin 762-00, Ohio State University. Web site accessed February 9, 2007 Hay can be analyzed by many laboratories and that is the most reliable way to tell the nutritional values it contains.
Hay, particularly alfalfa, is sometimes compressed into pellets or cubes. Processed hay can be of more consistent quality and is more convenient to ship and to store. It is also easily obtained in areas that may be suffering localized hay shortages. However, these more concentrated forms can be overfed and horses are somewhat more prone to choke on them. On the other hand, hay pellets and cubes can be soaked until they break apart into a pulp or thick slurry, and in this state are a very useful source of food for horses with horse teeth problems such as dental disease, tooth loss due to age, or structural anomalies.
Production quality also matters. If hay is baled with too much moisture, or if a dead animal, such as a snake or rodent, is caught in a bale, the subsequent botulism toxins released can contaminate the hay.
Haylage, also known as Round bale silage is a term for grass sealed in airtight plastic bags, a form of forage that is frequently fed in the United Kingdom and continental Europe, but is not often seen in the United States. Because haylage is a type of silage, hay stored in this fashion must remain completely sealed in plastic, as any holes or tears can stop the preservation properties of fermentation and lead to mold or spoilage. Rodents chewing through the plastic can also spoil the hay introducing contamination to the bale. If a rodent dies inside the plastic, the subsequent botulism toxins released can contaminate the entire bale.
Sometimes, straw or chaff is fed to animals. However, this is roughage with little nutritional value other than providing fiber, and is more often used as a bedding in stalls to absorb waste.Mackay, Bruce. Practical feeding of horses (PRIMEFACT 425) September, 2007, New South Wales, Department of Primary Industries. Web site accessed July 25, 2008 It is sometimes used as a filler; it can slow down horses who eat their grain too fast, or it can provide additional fiber when the horse must meet most nutritional needs via concentrated feeds. "Chaff or no Chaff?" Hygain news, web site accessed July 4, 2009.
are the most popular grain for horses. Oats have a lower digestible energy value and higher fiber content than most other grains. They form a loose mass in the stomach that is well suited to the equine digestive system. They are also more palatable and digestible than other grains.
maize (USA), or maize (British English), is the second most palatable grain. It provides twice as much digestible energy as an equal volume of oats and is low in fiber. Because of these characteristics, it is easy to over-feed, causing obesity, so horses are seldom fed corn all by itself. Nutritionists caution that moldy corn is poisonous if fed to horses.
Barley is also fed to horses, but needs to be processed to crack the seed hull and allow easier digestibility. It is frequently fed in combination with oats and corn, a mix informally referred to by the acronym "COB" (for Corn, Oats and Barley).
Wheat is generally not used as a concentrate. However, wheat bran is sometimes added to the diet of a horse for supplemental nutrition, usually moistened and in the form of a bran mash. Wheat bran is high in phosphorus, so must be fed carefully so that it does not cause an imbalance in the Ca:P ratio of a ration. Once touted for a laxative effect, this use of bran is now considered unnecessary, as horses, unlike humans, obtain sufficient fiber in their diets from other sources.
Soybean meal is a common protein supplement, and averages about 44% crude protein. The protein in soybean meal is high-quality, with the proper ratio of dietary essential for equids. Cottonseed meal, linseed meal, and peanut meal are also used, but are not as common.
Actual amounts fed vary by the size of the horse, the age of the horse, the climate, and the work to which the animal is put. In addition, Genetics factors play a role as some horse breeds tend to be (good doers), which means that they can thrive on small amounts of food and are prone to obesity and other health problems if overfed, and other breeds tend to be (poor doers), meaning that they are prone to be thin and require considerably more food to maintain a healthy weight.
are usually a good source for recommendations on appropriate types and amounts of feed for a specific horse. Animal nutritionists are also trained in how to develop equine rations and make recommendations. There are also numerous books written on the topic. Feed manufacturers usually offer very specific guidelines for how to select and properly feed products from their company, and in the United States, the local office of the Cooperative Extension Service can provide educational materials and expert recommendations.
When beet pulp is fed, a ration of to is usually soaked in water for 3 to 4 hours prior to feeding in order to make it more palatable, and to minimize the risk of choke and other problems. It is usually soaked in a proportion of one part beet pulp to two parts water. Beet pulp is usually fed in addition to hay, but occasionally is a replacement for hay when fed to very old horses who can no longer chew properly.
Some pelleted rations are designed to be a "complete" feed that contains both hay and grain, meeting all the horse's nutritional needs. However, even these rations should have some hay or pasture provided, a minimum of a half-pound of forage for every of horse, in order to keep the digestive system functioning properly and to meet the horse's urge to graze.
When horses graze under natural conditions, they may spend up to 18 hours per day doing so.Blikslager, Anthony. "Avoiding Colic Through Management." The Horse July 2008: 47-54. However, on modern irrigated pastures, they may have their nutritional needs for forage met in as little as three hours per day, depending on the quality of grass available.
Another factor when feeding forages is the level of various non-structural carbohydrates (NSC), such as fructan. Too high an NSC level causes difficulties for animals prone to laminitis or equine polysaccharide storage myopathy (EPSM). NSC cannot be determined by looking at forage, but hay and pasture grasses can be tested for NSC levels. Watts, Kathryn. "Finding and Testing Low-Sugar Forage," The Horse Web site, accessed May 16, 2007.
In general, the portion of the ration that should be grain or other concentrated feed is 0-10% grain for mature idle horses; between 20-70% for horses at work, depending on age, intensity of activity, and energy requirements. Concentrates should not be fed to horses within one hour before or after a heavy workout. Concentrates also need to be adjusted to level of performance. Not only can excess grain and inadequate exercise lead to behavior problems, it may also trigger serious health problems that include Equine Exertional Rhabdomyolysis, or "tying up", in horses prone to the condition. Another possible risk are various forms of horse colic. A relatively uncommon, but usually fatal concern is colitis-X, which may be triggered by excess protein and lack of forage in the diet that allows for the multiplication of Clostridium organisms, and is exacerbated by stress.
Even a slightly dehydrated horse is at higher risk of developing impaction horse colic. Additionally, dehydration can lead to weight loss because the horse cannot produce adequate amounts of saliva, thus decreasing the amount of feed and dry forage consumed. Thus, it is especially important for horse owners to encourage their horses to drink when there is a risk of dehydration; when horses are losing a great deal of water in hot weather due to strenuous work, or in cold weather due to horses' natural tendency to drink less when in a cold environment. To encourage drinking, owners may add electrolytes to the feed, additives to make the water especially palatable (such as apple juice), or, when it is cold, to warm the water so that it is not at a near-freezing temperature.
Incorrect feeding is also as much a concern as simple overfeeding. Ponies and miniatures need a diet relatively low in sugars and starches and calories, but higher in fibers. Miniature horses in particular need fewer calories pound for pound than a regular horse, and are more prone to hyperlipemia than regular horses, and are also at higher risk of developing equine metabolic syndrome.
It is important to track the weight of a pony carefully, by use of a weight tape. Forages may be fed based on weight, at a rate of about of forage for every . Forage, along with water and a salt and mineral block, is all most ponies require. If a hard-working pony needs concentrates, a ratio of no more than 30% concentrates to 70% forage is recommended. Concentrates designed for horses, with added vitamins and minerals, will often provide insufficient nutrients at the small serving sizes needed for ponies. Therefore, if a pony requires concentrates, feed and supplements designed specially for ponies should be used. In the UK, extruded pellets designed for ponies are sometimes called "pony nuts".
Donkeys, like mules, need less protein and more fiber than horses. Although the donkey's gastrointestinal tract has no marked differences in structure to that of the horse, donkeys are more efficient at digesting food and thrive on less forage than a similar sized pony.Smith, David and Stephanie Wood. "Donkey Nutrition." The Professional Handbook of the Donkey Duncan, James and Hadrill, David (2008) Whittet Books. Volume 4, p. 10. They only need to eat 1.5% of their body weight per day in dry matter.Wood, Stephanie, David Smith and Catherine Morris. "Seasonal variation of digestible energy requirements of mature donkeys in the UK". Proceedings Equine Nutrition Conference. Hanover, Germany. 1–2 October 2005:p. 39-40. It is not fully understood why donkeys are such efficient digestors, but it is thought that they may have a different microbial population in the large intestine than do horses, or possibly an increased gut retention time.Smith DG, Pearson RA. "A review of the factors affecting the survival of donkeys in semi-arid regions of sub-Saharan Africa." (Special issue: Nutrition and health of donkeys in the tropics) Tropical Animal Health and Production. 2005. 37: Supplement 1, 1-19.
Donkeys do best when allowed to consume small amounts of food over long periods, as is natural for them in an arid climate. They can meet their nutritional needs on 6 to 7 hours of grazing per day on average dryland pasture that is not stressed by drought. If they are worked long hours or do not have access to pasture, they require hay or a similar dried forage, with no more than a 1:4 ratio of legumes to grass. They also require salt and mineral supplements, and access to clean, fresh water.Aganga, A.A., et al. "Feeding donkeys" Livestock Research for Rural Development 12 (2) 2000. Department of Animal Science and Production, Botswana College of Agriculture. Web site accessed July 4, 2009. Like ponies and mules, in a lush climate, donkeys are prone to obesity and are at risk of laminitis. "Feeding Your Donkey" Web site accessed July 4, 2009.
However, if treats are allowed, carrots and compressed hay pellets are common, nutritious, and generally not harmful. Apples are also acceptable, though best if cored or sliced, as the seeds contain toxins. Horse "cookies" are often specially manufactured out of ordinary grains and some added molasses. They generally will not cause nutritional problems when fed in small quantities. However, many types of foods are potentially dangerous to a horse and should not be fed. This includes bread products, meat products, potatoes, , stone fruits, chocolate, and caffeinated beverages.
It was once a common practice to give horses a weekly bran mash of wheat bran mixed with warm water and other ingredients. It is still done regularly in some places. While a warm, soft meal is a treat many horses enjoy, and was once considered helpful for its laxative effect, it is not nutritionally necessary. An old horse with poor teeth may benefit from food softened in water, a mash may help provide extra Tissue hydration, and a warm meal may be comforting in cold weather, but horses have far more fiber in their regular diet than do humans, and so any assistance from bran is unnecessary. There is also a risk that too much wheat bran may provide excessive phosphorus, unbalancing the diet, and a feed of unusual contents fed only once a week could trigger a bout of colic.
It is generally not safe to give a horse feed that was contaminated by the remains of a dead animal. This is a potential source of botulism.Heusner, Gary. "Horse Feed Quality and Contamination" (PDF) Web site accessed July 4, 2009. This is not an uncommon situation. For example, mouse and can get into poorly stored grain and be trapped; hay bales sometimes accidentally contain , mice, or other small animals that were caught in the hay machinery during the harvesting process.
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