Nutrition and the Performance of Horses

by Robert N. Oglesby DVM

Introduction

The more we learn about nutrition the more the old basics seem to be the best way to feed horses for maintenance or light to moderate exercise. There are exceptions to these easy time-tested rules and one of them is horses performing at a high level of physical effort. Several nutritional problems start to appear at high levels of performance:

The inability to take in enough calories without overloading the digestive system with simple sugars and starches which may result is disease.
Increase energy production and catabolism of tissues resulting in performance limiting consequences:
1. a depletion of energy sources to the muscles
2. a build up of toxic products
3. a build up of heat in the tissues
A loss of excessive amounts of water and electrolytes during prolonged exercise, limiting performance and causing disease.
The weight of the food and water in the digestive tract which can have both detrimental and beneficial effects on performance depending on the endeavor.

Nutrition, supplementation, and feeding schedules all can affect performance. Feeding for performance has greatly changed the natural feeding patterns of horses and has profound effects on metabolism, performance quality, and even disease.

Not all performance horses face the same problems. There are unique metabolic problems to the sprinter who travels 1/4 mile or less, the middle distance horse who travels up to 2 miles, and endurance type endeavors, ...more. Recent research by the Kentucky Equine Research (KER) group has indicated we can make some improvements over traditional forage and grain recommendations. This article covers how nutrition affects performance, some of the recent findings of KER and then gives specific feeding regimens for various performance horse types, including racing, hunting, eventing, and endurance racing. Also, provided are links for more in depth discussions on specific topics.

Forage and Grain

Forage: hay is different from pasture

One of the problems of the hard exercising horse is that the amount of energy required to maintain weight and get the job done requires a diet that is limited in the amount of fiber. A horse can only eat so much food a day and if his caloric requirement is great enough it may crowd out the fiber portion of the diet. This has serious consequences on both digestive function and health including an increased incidence of: colic, founder, diarrhea, tying up, and stable vices. Horses should eat at least half, by weight, of their daily diet as forage.

When hay is fed as large separate meals it too can adversely affect health and performance in several ways:

Hay consumption in large separate meals causes a large redistribution of water from the horse's tissues to the digestive tract. Causing a transient but very real form of dehydration.
Hay consumption during a grain meal may interfere with optimum digestion of the grain and allow for increased bacterial fermentation of simple starches. The result is an increase in both endotoxin and blood lactate: a possible performance restricting chemical.
Large meals of hay can significantly increase the weight of the horse.

The following general guide lines will help you overcome some of these obstacles and further improve your horse's performance:

Pasture may be best but its quality needs to be carefully assessed for both over and under nutrition.
Always feed a fresh, top quality, dust free, hay.
Adapt your horse to eating their hay slowly free choice rather than as a big meal several times a day.

There are recommendations that may improve specific types of performance. For prolonged endeavors that require a good reservoir of water, fiber in the digestive tract can act as a water reservoir and at sub-maximal speeds may not affect performance remarkably. For short, fast endeavors the weight of the horse adversely affects performance. Withholding a meal or two before competition is not effective at reducing weight, however, restricting hay intake to 1% of body weight for the preceding 72 hours will reduce body weight up to 2.5 percent, ...more

Grains

The predominant natural fuels of horses are free fatty acids from microbial digestion of hay in the large bowel. Though used for thousands of years to feed horses, grains significantly alter the natural energy mechanisms. Grains dump large quantities of sugar in the form of glucose into the bloodstream.

After a large meal the high blood glucose levels result in the body mobilizing its hormones and chemistry to process this excess fuel for storage. If a horse is exercised during this period of "high blood glucose processing" a paradoxical thing happens: the blood glucose drops abnormally low. When the exercise was started, it was high. All of the body's machinery was engaged at lowering the levels, now comes along exercise that uses up much of the excess fuel in the blood and the body cannot switch off the storage mechanisms quickly.

So how long should you wait before exercising your horse after a big grain meal? We know three hours is too short a period and eight hours has been recommended by some. Currently five to eight hours is recommended to lapse between the last big grain meal and exercise. It also appears that putting vegetable oil (fat) over the grain decreases the rate at which grains are digested, further aiding in prevention of the glucose and metabolism spikes that accompany grain feeding. Just as with hay feeding, grain in many small meals is much better than several big meals. For More Information

Specific Nutrients

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Nutrition and Exercise Performance of Horses