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Fish Oil Supplementation for Exercising HorsesBy Kentucky Equine Research Staff · June 22, 2015

Though fish oil may sound like an unnatural feed for horses, it is a rich source of the omega-3 fatty acids that may be deficient in horses that have limited opportunity to graze and are given large grain meals.

University of Kentucky researchers performed a study to test the effect of fish oil supplementation on exercising horses. In the study, 13 horses of Thoroughbred or Standardbred breeding were assigned to either fish oil or corn oil treatment groups. All horses received timothy hay and a mixed grain concentrate at rates necessary to meet their energy needs. Oil was top-dressed on the concentrate daily at a rate of 324 mg/kg of body weight.  

The horses exercised five days each week for nine weeks in a program of increasing intensity. The researchers obtained blood samples before supplementation and on days 28 and 63. Following the training period, horses performed a standard exercise test on a high-speed treadmill, while the researchers gathered blood samples during exercise and recovery.

Compared to horses receiving corn oil, horses receiving fish oil had lower serum lipids and cholesterol at week four and lower serum triglycerides at week nine. During exercise, heart rates were lower for horses receiving fish oil, but no differences in plasma lactate were detected. Serum cholesterol was lower in horses receiving the fish oil treatment throughout exercise. Serum insulin and plasma free fatty acids were lower in horses receiving fish oil than in horses receiving corn oil during the initial stages of the exercise test. Plasma glucose was lower for the fish oil group during exercise recovery from 6 minutes to 30 minutes after exercise.

The researchers concluded that the addition of fish oil to the diet positively altered plasma lipid characteristics of horses, and may have had a desirable effect on insulin sensitivity and glucose metabolism in response to exercise.

EO-3, a dietary supplement developed by Kentucky Equine Research, is a rich source of omega-3 fatty acids in a palatable liquid form. EO-3 can be fed to all classes of horses, including foals, breeding stock, and performance horses to improve the critical ratio of omega-3 to omega-6 fatty acids in the diet.