How energy factors into your horse’s diet and the different ways to manipulate it

The definition of equine energy is as vast as the force itself. Barrel racers look to energy to increase their horses’ vigor, fueling the bursts of speed they need on the pattern. Dressage riders depend on energy for prolonged stamina as horses work in collection, performing advanced full-body movements. Trail riders count on it to sustain their mounts to the end of a full-day ride.

In this article Natalie Sullivan, MS, PAS, owner of On Course Equine Nutrition, and Carey Williams, PhD, equine extension specialist and professor at Rutgers School of Environmental and Biological Sciences and the Equine Science Center, in New Brunswick, New Jersey, shed light on what energy is and how it impacts horses in their work.

What Is Energy?

Everyone knows what energy is—at least they think they do.

Williams believes many people think of energy as what horses use to exercise, but it’s more than that. Energy supports life, and its definition is complex.

“How we get energy is by breaking chemical bonds with energy sources,” Williams says.

In less scientific terms, when a horse consumes food, his body must break it down before he can draw energy from it, she explains. In Williams’ opinion, energy units, which are measured as kilocalories or megacalories in horses, are one of the most difficult nutrition concepts to comprehend.

“The three ways that horses get energy from food is through carbohydrates, proteins, and fat,” Sullivan says, noting that each source provides energy in a different manner. Feeds often contain a combination of carbohydrates, proteins, and fat in different ratios. How these sources are prioritized in the diet impacts a horse’s performance or excitability.

Carbohydrates These come in several forms. Williams breaks them down into three categories:

• Structural carbohydrates are found in feed staples such as pasture grass and hay. It takes a lot of microbial fermentation over a long period in the large intestine for them to break down into energy.
• Hydrolyzable carbohydrates are sugars and starches, like what you’d find in grains such as oats and corn. They break down quickly in the small intestine and chemically react with water to change into glucose.
• Rapidly fermentable carbohydrates are found in feeds such as beet pulp and soy hulls and break down by microbial fermentation in the large intestine.

“The structural carbohydrates are what make up the bulk of most horses’ diets,” Williams says. However, she adds, they’re largely overlooked by horse owners.

Hydrolyzable carbohydrates are what equestrians, especially those involved in sports like barrel racing or jumping, often turn to for short-term energy or bursts of speed, says Sullivan.

Owners opt for rapidly fermentable carbohydrates when they want to harness the benefits forage fibers offer for maintaining gut health but provide more calories while doing so—often when adding condition to a hard keeper or providing extra fuel for performance.

Protein Horses convert protein to a type of energy that helps them build muscle. Williams points out that less than 10% of the energy in a horse’s diet typically comes from protein, however. She feels many horse owners and riders believe high-protein feeds cause their horses to act “hot.” They don’t realize how little protein contributes to a horse’s dietary energy and that it is rarely the reason a horse is excitable.

Fats These are 2.5 times more calorie-dense than carbs and are absorbed in the small intestine and don’t need to be fermented, says Williams. However, fats also take the longest to convert to energy. Fats encourage weight gain and are useful for horses competing in endurance sports, such as long-distance trail riding, because they release energy slowly. They are found in feeds such as rice bran, flaxseed, and oils.

Common Misunderstandings

Because of its complexity, energy is prone to being misunderstood. Sullivan says many people simply haven’t determined what they want from—or need for—their horse in terms of energy. To rectify this she recommends thinking about energy in one of three ways:

1. Measurable (digestible) energy to help a horse maintain, gain, or lose weight—how we’ve referred to energy up until now.
2. Energy as it relates to behavior (e.g., ­excitability).
3. Energy as it relates to performance (e.g., stamina).

“It’s extremely important to decide which of these three areas you are trying to manipulate before you start adjusting and experimenting with your feed program,” Sullivan says. “We can adjust the ratios of protein, carbohydrates, fat, and other nutraceuticals differently depending on which energy type you prioritize and if you want it to go up or down.”

A pitfall Williams encounters is when owners do not help their horses reach a healthy body condition score and fitness level before altering nutrition to influence behavior or performance. For example, she says giving an energy-rich feed to an unfit, overweight horse, hoping it’ll provide the horse more vigor during work, might result in the horse becoming obese.

“If you know that your horse is at a good body condition score and they’re at an appropriate level of fitness for the type and intensity of work you want to do, then we can look at diet,” Williams says.

To make sure you’re meeting your horse’s individual nutritional requirements (more on this in a moment), Sullivan advises following the label instructions on your bagged feed and working with an equine ­nutritionist.

Lastly, don’t confuse undesirable excitability, dullness, or other behaviors with underlying injury or illness. Williams encourages owners to rule out possible health concerns before adding or removing calories from a horse’s budget.

“Figure out, ‘Is it behavioral or is it training or is it pain?’ ” she says.

Questions to ask yourself include:

• Why do you think your horse needs more or fewer calories?
• Is it due to a behavioral issue?
• Could your horse be giving you a specific response because of pain?

For example, says Williams, a rider might complain that a horse is lazy or behind the leg, when those sluggish movements might be in response to pain from gastric ulcers.