Researchers say "Feed More Fat"

Researchers say "Feed More Fat"

by Steve Hill


Texas Agricultural Experiment Station researchers found that racehorses and cutting horses in competition could get an extra burst of energy from a diet with higher amounts of fat, which could increase stamina and help them avoid injury.


"Equine athletes become acutely fatigued and more susceptible to injury during their performances," said Dr. Gary Potter, a professor of animal science at Texas A&M University and an experiment station researcher. "Seventy percent of racehorses have career-ending or career-altering injuries, and 80 percent of those are musculoskeletal. Most of them also come toward the end of a performance, so we're looking for ways to delay the onset of acute fatigue."


The researchers think they have one way. They have found horses can not only handle more fat in their diet, but that equine athletes adapted best to the diets after periods of three to four weeks. Potter said that, previous research had shown a moderately high-fat diet in horses produces a glycogen "sparing" effect that increases glycogen stored in muscle. Glycogen is a carbohydrate readily converted to glucose for energy use.


Potter and other experiment station researchers set out to determine how far in advance of a performance horses should be given more fat to increase caloric benefits. "A typical horse diet contains 2 to 3 percent fat, so they're not adapted to fat as a fuel source," Potter explained. "You can't just give a horse more fat the day before a race and expect it to perform better. They have to adapt."


Potter's team searched for the answers in two different experiments: one involving eight racehorses and one with eight cutting horses. In each experiment, the horses were fed a 10 percent fat-supplemented concentrate in their diet in one period, than were given a normal diet in a control period. Every seven days afterward, the Thoroughbreds were put through a standardized running exercise that included three 400-meter sprints in addition to other running. The Quarter Horses were worked with a mechanical "cow" in a standardized movement routine simulating a cutting horse event. Before, during and after each exercise test, each horse's heart rate, respiration rate and rectal temperature was taken, along with a series of blood samples. In addition, a muscle biopsy was obtained from the biceps femoris, a large leg muscle, in each horse both before and after the test.


The researchers found that muscle-glycogen storage and use peaked after 21 days for Thoroughbreds on The higher-fat diet, but at 28 days for cutting horses. Potter thought the difference was a result of the differing rates at which The equine athletes reached their best competitive condition. "I doubt that the exercise test for cutting horses was as hard as for the Thoroughbreds," Potter said. However, he said, it could be that cutting horses could adapt even more to a higher-fat diet, because no tests were taken after 28 days. "I don't know whether we would have seen a plateau for cutting horses at 35 days," he said. The experiment wasn't carried on beyond 28 days because earlier research had shown that horse can reach their peak fitness after three weeks of training.


The researchers also had a second major question. Whether increased fat intake would have digestive drawbacks for the horses. But they discovered fiber fermentation in the large intestine was not adversely affected even when up to 18 percent fat supplement was added to horse's diets. However Potter said that, he is not sure that amount of fat is beneficial. He also added that he harbored no illusions that either diet or training could make a slow horse fast.


Potter does recommend adding 7 to 10 percent fat to an equine athlete's diet at least three weeks before a performance. For those training competitive horses, Potter also had words of wisdom that have been heard on fields and courts throughout the human athletic would. "In that three weeks, they should do some really strenuous work."


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