Nutrition: Monitor, Manage Horse Energy Intake

Eating well is not always eating safely; horse managers who ignore that lesson when feeding their animals might be creating digestive problems for their horses.

"Many feeding management recommendations for horses are related to supplying energy safely," said Dave Freeman, PhD, PAS, Dipl. ACAN, Oklahoma State University Cooperative Extension equine specialist. "Most of the energy supplied in rations comes from carbohydrates. There are two types of carbohydrates, the 'starchy, sugary' carbs and the 'fibrous' carbs. The two types vary in how and to what extent they are digested."


One source of energy that horses rely on is fiber. Hays and pastures supply energy in the form of fiber. Typically, horses should have access to pastures, hays or coarsely processed forage at minimum levels of 0.75% of bodyweight per day. These levels guard against feeding too much of the other type, the 'starchy, sugary' compounds.

"Incorporation of long-stem forage into rations also increases particle size of substances ingested, thus slowing the rate of intake and the amount of digestible nutrient intake in a single meal," Freeman said. "Slowing the rate of intake and decreasing the digestible energy intake in a single meal may assist digestion in the horse's small intestine."

Starchy and sugary carbohydrates

On the other hand, grains are low in fiber. They supply large amounts of starchy and sugary carbohydrates as compared to forages. If allowed free access, most horses will consume enough grain to cause digestive upset. The most common problem with equine overeating is the consumption of too much starchy or sugary carbohydrate in a single feeding.

"Grains vary in the amount of starch; for example, corn has more starch per pound than oats," Freeman said. "Knowing the energy concentration of the grain mix will assist in determining the amount of ration that is needed to supply a horse's energy needs."

Generally, the higher the fiber content, the lower the digestible energy content. Crude fiber estimates on feed tags can provide useful information in this regard. Additionally, added-fat feeds will raise or maintain the energy level of feeds while reducing the amount of starch.

Horses in a positive energy balance will store energy as fat. Body fat is reduced when the ration does not provide sufficient nutrients to maintain energy balance. Accurate assessment of a horse's fat cover allows for visual appraisal of the animal's energy status.

"In general, most horses should be fed a balanced ration at levels that produce moderate to fleshy body condition, thus avoiding extremely thin or obese conditions," Freeman said.

Assess body condition

Routine assessment of each horse's body condition is necessary because horses in similar production and weight classes will vary in their nutrient needs.

Freeman said while horse managers commonly group together horses in similar production and weight classes, animals in abnormally high or low body condition might need to be separated further to help ensure the individual needs of each animal are met.

"Once horses are grouped, horse managers need to assess energy sources, levels and utilization of feedstuffs," he said.

Freeman cautions it is important that changes in intake level and the physical form of rations be done gradually, the recommended time period being several days to weeks. This practice allows a horse's digestive tract time to adapt to different levels and physical forms of nutrients.

"Gradual changes are especially important when feeding energy-dense rations," he said. "Grain amounts should be increased incrementally when changes in management require an immediate need for additional energy; increasing grain one-half pound every two to three days until the energy balance is met is a common recommendation."

The technique also is useful when introducing horses to pastures with large amounts of lush forage; as similar to grains, there are types of carbohydrates that cause colic and founder if too much is eaten too quickly. Simply limit access for several days when horses are not accustomed to eating lush forages.

"Remember, in times when forages are especially lush and in large supply, even horses that are accustomed to eating forages may need amounts restricted," Freeman said.

Food weight not volume

One method many horse managers find useful is to feed horses by the weight of the ration rather than its volume.

"Feeding by weight will decrease the chance of overfeeding because of differences in weight per volume of different feeds and different processing methods," Freeman said.

For example, corn weighs more per volume than oats, and pelleted feeds weigh more per volume than textured feeds.

"Horse managers need to weigh feed periodically to ensure accurate monitoring of intake by horses," Freeman said. "This is especially important when changing feed sources; one of the most common causes of digestive upset is overfeeding energy in a single session because differences in weight of grain mixes were not taken into account."

Processing also typically increases digestibility of hard-seed coat grains and assists in intake of ingredients with different particle sizes in a mix. Pelleting, micronizing, flaking, rolling, cracking, wafering, and extruding are examples of processing methods that are considered acceptable by the horse industry.

"Small-seed grains with hard-seed coats such as milo and wheat should be processed to increase utilization of ingredients," Freeman said. "The benefit of processing soft-seed coated grains, such as oats, is much less."

Horses with poor dentition might benefit more from processed food than other animals. This is often a consideration with older horses. Also, the value of processing is increased when feeding large quantities of grain to horses with limited capacity, such as rations fed to growing horses to obtain maximum gain.

"In many ways, the horse's digestive physiology is best suited for a continuous low-level supply of feed," Freeman said. "However, management, housing, and production needs dictate that most horses are meal-fed."

To meet the requirements of both horse and owner, Freeman suggests grain mixes be split into two daily feedings when the daily amount of grain exceeds 0.5% of the animal's bodyweight (five pounds for a 1,000-pound horse).

"Those feeding grain to horses at levels of 1% or greater of the animal's bodyweight should consider splitting amounts into three portions per day," he said.

In any case, meal feedings should be separated as much as possible, 10 hours to 12 hours between morning and evening feedings for two daily meals being a common recommendation.

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