Energy Use in Exercising Horses

Horse feeds usually contain several energy sources such as grains and fat products. As they exercise at different levels of intensity and for various lengths of time, horses use dietary energy in predictable ways.

There are two important concepts concerning energy metabolism during exercise of low to moderate intensity exercise. First, in the early part of exercise, carbohydrates are the predominant substrate for energy production, with minimal contribution from lipid (fat) sources. Conversely, after one hour of work the contributions by carbohydrates and fats to energy production are almost equal. During longer but lower intensity work, such as that expected of an endurance horse, the proportion of energy derived from fats would be even higher.

Second, the greater efficiency of energy production from fats is illustrated by the progressive decrease in the rate of energy expenditure over the course of the exercise bout. That is, with increasing exercise duration, less energy (and, therefore, lower heat production) is required to sustain the same amount of work.

Horses performing in most disciplines will get along well on rations that provide energy from both carbohydrates and fats. Owners should consult with an equine nutritionist if they have questions about the best feed formulation for a specific horse in a particular discipline.