Q: My 8-year-old jumper struggles to build muscle over his topline and seems to fatigue easily during exercise. Can you explain what might cause this? How can I adjust his diet to help improve his condition and energy?

A: A balanced diet—one that meets the recommended essential nutrient amounts as outlined in the Nutrient Requirements of Horses, 2007—is critical to horse health and performance. If your horse seems to have issues with muscle development and low energy levels, an equine nutritionist should evaluate his diet.

Because underlying health conditions can cause the same or similar signs, always consult your veterinarian to rule out medical issues.

Nutrition for a Performance Horse’s Topline

To support topline development feed your horse’s a balanced diet with emphasis on high-quality protein and adequate digestible energy (calorie) intake. A high-quality protein source means one rich in essential amino acids, particularly lysine, methionine, and threonine. Examples of high-quality protein sources for horses include soybean meal, alfalfa, and whey protein.

Forage—generally hay or pasture—should make up the bulk of a horse’s diet. However, the quality can vary significantly depending on numerous factors such as plant maturity and forage species. Some forages readily meet the calorie requirements of a working horse when provided at about 2% of the horse’s body weight daily. Other forages could be lower in calories, which means you need to supply additional digestible energy.

Another consideration to make when it comes to calorie supplementation involves the type of calories to add. For example, fats and carbohydrates both provide calories but in different ways. Your horse fatiguing easily might stem from too few calories in the diet or also the wrong type of calories.

Calorie Sources for Horses

Carbohydrates supply most of the calories in the horse’s diet, with fats and proteins contributing as well. Adequate carbohydrate intake supports the energy demands of work and performance.

Generally, nutritionists group carbohydrates into one of three categories: hydrolyzable, rapidly fermentable, or structural carbohydrates. The horse breaks hydrolyzable carbohydrates down in the foregut (the stomach and small intestine), digesting them quickly for energy, and digests both rapidly fermentable and structural carbohydrates in the hindgut (the large intestine).

Choosing a performance feed that provides supplemental carbohydrates, along with high-quality protein, promotes appropriate energy levels for sport horses. Note that if your horse does not need the full manufacturer’s recommended amount, you must add a ration balancer to fill any nutrient gaps.

Take-Home Message

To improve your performance horse’s energy levels and help him build muscle, first work with your veterinarian to rule out health issues. Once you resolve any physical problems, rely on a high-quality forage as the base of your horse’s diet and add a well-fortified performance feed.

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