Feeding Management for Stressful Situations

"Anytime you ask a horse to be a performance horse (taking him out of his natural environment), you put him in a stressful situation," said Joe Pagan, PhD, owner of Kentucky Equine Research (KER) in Versailles, Ky., during his presentation "Feeding Management of Horses Under Stressful Situations" at the 2002 KER Equine Nutrition Conference. "Feeding management is of critical importance to reduce many of these problems (related to stress). Additionally, pre-competition feeding can significantly affect performance."

Pagan recently completed a study that evaluated how various feeding programs affected body weight and energy expenditure. Conditioned Thoroughbreds were used for the study, which found that compared to free-choice access to hay (in which horses ate 22.3 pounds, or 10.1 kg, on average), restricted hay intake (in which horses ate 9.5 pounds, or 4.3 kg, on average) resulted in about a 2% decrease in body weight and an increase in the mass-specific rate of oxygen consumption during spring exercise, with a corresponding decrease in anaerobic energy expenditure. Thus, the horses weren't working as hard because of a reduction in body mass. This is roughly the same effect that one gets with Salix, a diuretic medication (one that draws water from body tissues and thus promotes urination). Pagan cautioned that this type of hay restriction is only appropriate a few days before intense exercise such as Thoroughbred racing. At all other times, performance horses should eat liberal quantities of forage.

Gastric Ulcers--Pagan also discussed the prevalence of gastric ulcers in equine athletes, noting their extremely high occurrence (80-90% in training racehorses). Gastric protectants such as Neigh-lox don't cure ulcers, but can make horses feel better by coating the mucosal surfaces and buffering excess stomach acid. The only licensed drug for treatment of ulcers in horses is omeprazole (GastroGard), which decreases the acidity of the stomach by inhibiting acid production. Ulcers are extremely rare in horses maintained solely on pasture; "Indeed, the most effective way to treat ulcers is simply to turn the animal out on pasture," Pagan stated. "If this is not possible, gastric protectants such as Neigh-lox may be a useful adjunct to aid acid suppression therapy."

Feeding Before Competition--KER frequently gets questions about optimal feeding management before competition; the firm recently completed three experiments on this subject with the Waltham Centre for Equine Nutrition and Care in England. Feeding grain with or without hay two hours before exercise reduced free fatty acid (FFA) availability and increased glucose uptake, which is not efficient for prolonged exercise. Feeding only forage before competition did not affect FFA availability, and might only increase body weight slightly. If forage is fed in small amounts, this increase would probably be very slight.

Electrolytes--These are critical to performance horse nutrition because "they play an important role in maintaining osmotic pressure, fluid balance, and nerve and muscle activity," explained Pagan. Sweat losses of these nutrients can be very high in hard-working horses and those in hot climates, and thus supplementation might be necessary. He recommended daily electrolyte supplementation for horses at work, and additional supplementation for days when training is especially long or the climate hot and humid. "As a rule of thumb, two ounces (60 grams) of electrolyte supplementation are required for each hour of exercise in moderate climates," he said. "This rate of supplementation will double in hot environments when sweat loss is extensive."

He also said that horses must have drinking water available when given electrolyte paste. For an endurance horse, the best way to "load" him with water and electrolytes before a competitive ride is to have the horse on a high level of forage intake (to store water in the gut) and supplement electrolytes the night and morning before a ride. During the ride, electrolytes should include calcium and magnesium along with sodium, potassium, and chloride to prevent thumps and other metabolic disturbances.

Fat Adaptation--Feeding fat is a hot topic for performance horses, and KER set out to see if horses could adapt their metabolism to a high-fat diet, burning more fat and thus reducing fatigue. The two groups of horses studied received 7% and 29% fat diets, and the higher-fat group exhibited a reduced reliance on carbohydrates for energy after five weeks of supplementation. This "would preserve this more limited energy resource and delay the onset of fatigue associated with carbohydrate depletion," said Pagan, which would be helpful during prolonged exercise.

For more information on the KER conference, see the KER Equine Nutrition Conference section under Convention Reports at www.TheHorse.com.

About the Author

Christy M. West

Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.

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