How Does Chromium Supplementation Affect Strenuously Exercising Horses?

Six trained Thoroughbred horses were used in a two-period switchback design experiment to evaluate the effect that chromium supplementation has on metabolic response to a standardized exercise test (SET) on a high-speed treadmill.

During each 14-day period, the horses were divided into two groups and fed 3.64 kg of a textured grain mix, 2.73 kg of an alfalfa/oat plant forage cube, and 3.64 kg of orchard grass hay. One group (3 horses, CHROM) also received 5 mg of chromium from a chromium yeast product. For the first 12 days of each period, the horses exercised 3 days per week (1 mile at a 4m/s trot and 1 mile at 7-10 m/s) on a high-speed treadmill. At the end of each period, the horses performed an SET on the treadmill 3 hours after eating 1.82 kg of grain. The SET consisted of a 2 min warm-up walk followed by an 800 m trot (around 4 m/sec), then 800 m gallops of 8 m/s, 9 m/s, 10 m/s, and 11 m/s. These gallops were followed by an 800 meter warm-down trot and 2 min walk. At the end of each speed, heart rate was measured and a blood sample. Blood samples were also taken at 15 and 30 minutes after exercise. After period 1, the diets were switched and the protocol was repeated.

Blood insulin was lower in the CHROM group 1 hr after grain feeding. Blood glucose was significantly lower in the CHROM group after the 8 m/s and 9 m/s steps. Plasma lactate was lower in the CHROM group after the 11 m/s step. Cortisol was significantly lower in the CHROM group 3 hours after feeding, after the warm-up trot, and after the 8 and 11 m/s steps. Heart rate was unaffected by diet. These data suggest that 5 mg of daily supplemental chromium as chromium yeast affects metabolic response to a SET in fit Thoroughbred horses. These responses included reduced lactate and cortisol production which would be beneficial for strenuously exercised horses.

This report of KER’s 1995 research was published in Proceedings of the 14th Equine Nutrition and Physiology Society Symposium.

Read the entire research report, titled The Effect of Chromium Supplementation on Metabolic Response to Exercise in Thoroughbred Horses.