Free fatty acids in exercising Arabian horses fed two common diets

Four Arabian geldings were used in a randomized, repeated measure design to study the effect of two different diets on plasma free fatty acids at rest and during exercise. On each of four sampling days, two horses were fed one of two isoenergetic diets, either 100% corn or 100% alfalfa, at 22% of their estimated daily energy requirement. Two hours after the consumption of the diet, each horse participated in a submaximal standard exercise test consisting of three consecutive 10-min runs of increasing intensity at heart rates of 132, 140 and 147 beats/min, respectively. There were no significant (P greater than 0.05) differences between the two groups (corn-fed vs. alfalfa-fed) in pre-meal (0.554 +/- 0.031 vs. 0.629 +/- 0.033 mmol/L), post-meal (0.520 +/- 0.027 vs. 0.609 +/- 0.041 mmol/L), and basal (0.392 +/- 0.036 vs. 0.401 +/- 0.052 mmol/L) free fatty acid concentrations. However, free fatty acids were significantly higher in the horses fed alfalfa (0.608 +/- 0.038 mmol/L) rather than corn (0.484 +/- 0.031 mmol/L) during exercise.