These days, horse owners know more about equine health issues, saddle fit and horse psychology than they ever have before. Yet there is still one area that mystifies many horse experts and fosters debate among others: equine nutrition.

The question of what horses should eat remains a topic of much discussion in the horse world. The truth is that a simple answer is not easy to come by.

Why? Horses have individual nutritional needs based on their age, breed, lifestyle and even temperament. Further, research has not focused specifically on what horses should eat, but only on the generalities of equine nutrition.

Despite this, horse owners can determine the fundamentals of a good diet for their horses by doing some research and listening to what experts in equine nutrition recommend.

FEEDING THE AVERAGE HORSE

Just as with humans, horses need fat, carbohydrates and fiber in order to sustain healthy bodies. How much of each of these elements, however, is not clear-cut.

“The National Research Council (NRC) makes no recommendations about how much fat or carbohydrates a horse must have, so there are no hard and fast numbers on this,” says Karen Davison, Ph.D., manager of Equine Tech Services for LOL Purina Feed in St. Louis, Mo. “They do make a recommendation for omega-6 fatty acids, but not for omega 3s.”

Eric Haydt, vice president of sales and marketing for Triple Crown Nutrition, points out that although the NRC is silent when it comes to the minimum amount of fat or carbohydrates required by the average horse, the organization does recommend horses receive a minimum of one percent of their of ideal body weight in fiber each day.

To help determine the amount of fat and carbohydrates a horse needs, equine caretakers must look at the horse’s activity and metabolism level, type and quantity of hay, and a number of other issues, notes Haydt. Horses at a higher level of performance require more carbohydrates than horses that are enjoying a maintenance level of exercise, for example.

Providing fat in the diet is a safe way to provide calories, allowing owners to reduce grain intake to horses on high-fiber diets. Fat also provides calories to horses that are eating high-fiber diets that are naturally lower in calories than grain-based diets.

Carbohydrates are needed for energy, but can be tricky to provide. Higher levels of carbohydrates can increase the potential of colic, ulcers, hyper-activity and cribbing in some horses.

For all these reasons, the NRC provides a fiber minimum and leaves the amount of fat and carbohydrates up to owners and caretakers.

Emily Lamprecht, Ph.D., innovation development manager, consumer nutrition for Cargill Animal Nutrition in Minneapolis, Minn., (makers of Nutrena) notes that only nutrient requirements such as protein, vitamins, and minerals, as well as energy (Mcals) are specified by the NRC.

“Overall, forage should be the basis of the horse’s diet. Then the way we meet a horse’s additional caloric requirements is subject to interpretation of the latest research assessing how different sources of energy—primarily carbohydrates and fat—are digested and utilized by different classes of horses,” she says.

“What you feed your horse should depend on the individual horse and what he needs,” says Davison. “Look at your horse’s age and activity level, and consider the quality of your forage. The quality of your forage determines how you build the rest of your horse’s diet.”

Davison explains that the better the quality of forage and the less active the horse is, the less you need from other types of feed.

“If you are feeding a lower quality of forage and your horse is more active or is lactating, for example, there will be more demands for additional nutrition,” she says.

CARBOHYDRATES

“The primary source of energy in a horse’s diet comes from carbohydrates—including sugars, starches and fiber—as well as fat or oils,” says Lamprecht. Protein can be utilized for energy production, but it is not a primary energy source.

Non-structural carbohydrates (NSC) are an important component of a horse’s diet, says Lamprecht. NSCs include sugars and most of the starches. Sources include cereal grains, pastures, grass hays such as timothy and orchardgrass, legume hays, as well as carrots and other treats.

Unlike fiber, which is fermented in the hindgut, NSC are enzymatically digested in the small intestine. “In cases of starch overload, perhaps resulting from a large grain meal, the starch is not properly broken down and absorbed in the small intestine and progresses to the hindgut where it is rapidly fermented, causing various digestive disturbances,” she says. “It is important to feed controlled levels of NSC, based upon body condition and activity level, for prevention of digestive upset as well as for attaining optimal performance.”

Hard-working performance horses rely on NSC for energy during exercise and recovery so they can replenish energy stores efficiently. On the other hand, a maintenance horse with a low activity level will need far less NSC, says Lamprecht.

Too many carbs in the form of NSC can adversely affect some horses, says equine nutritionist Juliet Getty, Ph.D., author of “Feed Your Horse Like a Horse” (Dog Ear Publishing). “Horses that are insulin-resistant or suffer from equine Cushing’s disease and other disorders that require a low starch/low sugar diet should not have more than 12 percent NSC in the entire diet,” she says.

FATS

Fats are a necessary component of the horse’s diet, for the absorption of fat-soluble vitamins and for the provision of essential fatty acids. Additionally, fat is the most energy-dense nutrient, providing 2.5 times as much energy when compared to carbohydrates, says Lamprecht. Fat is well tolerated by horses.

Lamprecht notes that typical horse rations are generally low in fat (under three percent), however the commercial equine feed market is showing a trend toward higher-fat feeds and supplements.

Research has shown that horses adapt well to a high fat diet and actually will selectively “burn” fat over their glycogen energy stores, sparing these energy reserves for when they are needed most. For this reason, fat added to the diet can replace a certain amount of NSC, decreasing the risk of starch overload and the associated dietary disturbances.

Fat-adapted horses have been shown to have a mildly reduced water requirement, decreased fecal output due to reduced feed intake, reduced heat load, and were less excitable when compared to horses on a low fat diet, according to Lamprecht.

“It has also been suggested that equine athletes adapted to a higher-fat diet (around 11 percent) may experience a delayed accumulation of lactic acid and therefore a delayed onset of fatigue during exercise,” says Lamprecht.

Overall, adding fat is a great way to increase caloric content of the diet without asking the horse to eat large quantities of feed, she adds. This reduces the risk of digestive disturbances, and may provide some performance benefits to the equine athlete.

Fat takes several forms, and the overall diet should ideally have no less than two percent fat, according to Getty. “However, underweight horses and those that work need far more than this, generally in the 6 to 12 percent fat range,” says Getty.

Getty recommends flaxseed meal or oil as a source of fat for horses. She says that feeding soybean oil and corn oil can lead to inflammation due to high omega 6 fatty acid levels in these oils. Omega 3 fatty acids, from flaxseed meal in particular, have the opposite effect.

FIBER

The most important feedstuff for horses is fiber, found most often in the form of hay. In general, the average horse should consume 1 to 1.5 percent of its body weight in hay or pasture.

Fiber is essential to the horse’s digestive health and serves as a significant source of energy, notes Lamprecht. Fiber is found primarily in forages (hay and pasture), as well as things like beet pulp and soy hulls. “Fibers are digested through microbial fermentation in the hindgut—the cecum and large colon—of the horse, which produces the volatile fatty acids utilized by the horse for energy,” she says.

“The majority of a horse’s diet should be from fiber,” adds Getty. “I like to see at least 18 percent fiber in any commercial feed.”

According to experts, feeding horses is more complex than just tossing them a flake of hay a few times a day. A good equine feeding program requires knowledge and analysis. “It is always advisable to work with a trusted equine nutritionist or veterinarian to make sure the total diet is properly balanced,” says Lamprecht.

Special Cases

Not all horses should eat the same. Equines with specific issues should be treated differently when it comes to their diet. Here are some of the issues and their solutions.

Underweight: “The first thing to address is, has this horse always had trouble maintaining weight, or is it a new problem?” says Eric Haydt, vice president of sales and marketing for Triple Crown Marketing in Wayzata, Minn. “If it is an ongoing problem, the horse is probably a nervous type or just has a high metabolism. In this case, you just need to provide more calories.”

Calories can be provided by feeding more hay. Many horse owners believe that feeding 2 to 3 pounds per day is a lot of feed, yet most minimum feeding recommendations start at 5 to 8 pounds per day, says Haydt.

“If the amount of feed is already approaching an excessive level—1 percent of body weight per day—then feed a diet higher in fat, or supplement fat by using a flaxseed supplement,” he says. “Feeding a highly digestible high fiber/high fat diet helps eliminate some of the negative effects of high grain intake while still providing a higher level of calories.”

Overweight: Overweight horses respond best to a combination of increased exercise and a gradually restricted calorie intake, according to Emily Lamprecht, Ph.D., innovation development manager, consumer nutrition for Cargill Animal Nutrition in Minneapolis, Minn. “If the horse is on pasture, the amount of grazing time may need to be restricted, or the horse may need to be muzzled or placed in a dry exercise lot.” Grain, if being fed, may need to be reduced, or the horse switched to a lighter-calorie commercial feed or ration balancer.

“The horse’s diet still needs to be balanced for amino acids, vitamins and minerals to maintain muscle tone and overall good health, and as always, forage should be the basis of the diet,” says Lamprecht. If the horse has not been getting regular exercise, adding light exercise of at least three hours per week will be beneficial.

Under two years of age: “Horses under the age of two require a higher level of nutrition in order to build skeleton and muscle,” says Haydt. “This requires a feed designed specifically for foals.” These feeds have higher levels of protein, vitamins and minerals required for proper growth.

“Do not confuse fat with proper growth,” Haydt warns. “You can add weight to young horses by adding calories without a sound structural system for support.”

Research has also indicated that high-fiber foal diets have benefits for horses that may be prone to DOD (Developmental Orthopedic Disease) as compared to grain-based diets.

Senior: Change comes with age, and older horses may have trouble keeping on weight, often caused by issues with chewing. A decline in immune function can also develop along with allergies, diminished muscle mass and stiff joints.

For senior horses having trouble keeping weight on and chewing, equine nutritionist Juliet Getty, Ph.D., author of “Feed Your Horse Like a Horse” (Dog Ear Publishing) recommends a complete senior feed, which is easier to chew and digest. She also recommends moistening hay before feeding, since older horses have a reduced ability to produce saliva. Omega 3 fatty acids and Vitamin C supplementation are also important for older horses since these supplements reduce inflammation and boost the immune system.

Vices: Vices such as cribbing, weaving and pacing may be the result of boredom, lack of sufficient turnout time or physical activity, and stress from stall confinement or isolation from other horses, says Lamprecht. Discomfort from gastric ulcers has also been correlated to these types of behaviors.

Once started, these vices are difficult to manage. Some horses will lose body condition, damage or wear down incisors, or put unnecessary stress on joints.

Increased exercise, turnout and adding fat to the diet while avoiding high starch and sugar may be beneficial, she says. From a management standpoint, providing smaller meals more frequently as well as providing hay throughout the day in between concentrate meals, perhaps in a haynet or feeder that slows rate of consumption, can help keep horses occupied, says Lamprecht. Continuous eating also promotes saliva production, which can help neutralize stomach acid. This can reduce the occurrence or severity of gastric ulceration. —AP

Audrey Pavia