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by Casie Bazay

Why is digestible energy for horses important?

Why is digestible energy for horses important?

The physical capabilities of the horse are astounding. Whether it’s jumping six foot fences, racing at over 40 miles per hour, or gliding through a pirouette in the dressage arena, there is no denying their exceptional athletic ability. But just like human athletes, horses can only go as far as their level of fitness and nutrition allows. 

There’s a reason many feed and supplement companies have nutritionists, veterinarians, and other equine professionals on board; creating the ideal diet, especially for the performance horse, is a science. And at the top of the list for designing a feed is the amount of energy it will provide. 

Horses need energy not only to carry out daily essential functions such as digesting and absorbing food and for growth, but also for daily activities and performing whatever tasks we ask of them. 

In fact, the energy needs of an equine athlete can be more than twice that of an adult horse at maintenance. 

It’s important to keep in mind that no matter the work level, all horses are designed to consume grass as their main source of energy.  However, this can be a problem for performance horses, as grass won’t be enough to meet daily energy requirements. Hence the need for energy-dense concentrates, but it’s a careful tightrope to walk as overfeeding grain and underfeeding forage can increase your horse’s risk for digestive upset or certain muscle disorders.

What is digestible energy?

The total amount of energy contained in a feedstuff is referred to as gross energy (GE). However, GE is not a reliable indicator of the energy that will be directly available to the horse. Therefore, feed companies use digestible energy (DE) which amounts to GE minus the amount of energy lost in feces. 


There are several ways that the energy content of a feed can be estimated and one involves the heat of combustion, determined by using a bomb calorimeter in order to measure the amount of heat a feed produces when burned. 

Digestible energy is determined by subtracting the calorie content of feces from the calorie content of the feedstuffs to determine the amount of energy absorbed by the horse and therefore available for energy metabolism. 

The basic unit of heat energy is the calorie, which we’re all familiar with, but in technical terms, a calorie is defined as the amount of heat required to raise 1 gram of water 1 degree Celsius. However, because the calorie is too small to use in horse nutrition, energy content of horse feed is typically shown in megacalories (calories x 1,000,000) compared to the kilocalories (calories x 1000) used in human nutrition. 

Types of energy in the equine diet

Energy in a horse’s diet can be derived from three main sources: fat, carbohydrates and protein. Each of these nutrients and their ingredient sources provide different amounts of digestible energy. However, the highest amounts of energy in the equine diet come from carbohydrates and fats. 

Design the performance horse’s diet with DE in mind

So how much energy does a horse need? According to the National Research Council (NRC), here are the minimum requirements for an 1,100 pound horse:

  • Horses at maintenance (non-working): approximately 16 Mcal of DE daily;
  • Horses in light work (1-3 hours riding per week): approximately 20 Mcal of DE daily;
  • Horses in moderate work (3-5 hours of work per week): approximately 23 Mcal DE daily;
  • Horses in heavy work (4-5 hours riding per week with substantial time spent cantering); approximately 26 Mcal DE daily; and
  • Horses in very heavy work (6-12 hours work per week): approximately 34 Mcal DE daily.

FullBucket’s senior nutritionist, Dr. Amanda Bradbery, explains, “Digestible energy requirements for performance horses are determined based on the intensity and duration of the work. While duration is quite easy to determine, estimating intensity is difficult.”  

No matter the horse’s work level, forage should make up 1% of body weight per day. Endurance or cross country horses can benefit from receiving a diet of 75% forage, and for horses in moderate work or with a nervous temperament, a higher percentage of forage in the diet can be beneficial as well.

High quality pasture and hay provides adequate amounts of digestible energy for horses at maintenance, with legume hays such as alfalfa being higher in DE than grass hays. Keep in mind that less mature hays have higher digestibility and DE content than more mature hays. Additionally, getting your hay tested can provide a good estimate of the amount of DE, as well as other nutrients, it provides.

After good quality forage comes choosing a concentrated feed with an adequate amount of DE for your performance horse. However, the best type of feed will depend on the type of work your horse is doing. Fats are stored in adipose tissue and in and around muscle fibers while glucose (converted from carbohydrates) is stored as glycogen in muscle and the liver. 

For galloping exercise, muscle glycogen is the most important fuel source. However, for lower intensity exercise such as trotting and cantering, fat provides a better fuel source. 

Dr. Bradbery clarifies, “Feed tags list DE which can be useful in feed selection; however, does not represent where the energy comes from: carbohydrates (structural or non-structural) or fat.  To determine the source of energy in the diet, consider the crude fiber and crude fat levels.  If crude fiber and fat levels are high, non-structural carbohydrates will be low.  On the contrary, if crude fiber and fat are low, the feed is high in non-structural carbohydrates. It is important to understand your horse’s work level, DE requirements, and preferred source of energy when selecting a performance horse feed.”  

Enhance performance with energy supplements for horses

For serious competitors, consider FullBucket’s top-notch horse energy supplement. Athletic Formula is a great way to enhance feed digestibility and meet nutrient requirements. Containing probiotics, prebiotics, digestive enzymes, as well as vitamins and minerals, Athletic Formula optimizes digestive function, which increases nutrient absorption and supports your horse’s natural gut microbiome.

Read More:

  • https://www.extension.iastate.edu/equine/blog/dr-peggy-m-auwerda/energy-feed-ingredients-and-horse
  • https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/digestible-energy
  • https://thehorse.com/13870/high-energy-horse-feeds/

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