Antioxidant supplementation and subsequent oxidative stress of horses during an 80-km endurance race.

The research article investigates the impact of antioxidant supplementation (particularly vitamin E and C) on the development of oxidative stress in horses during an 80-km endurance race.

Methodology

• The study involved 46 horses that had been matched based on their past performances.
• The horses were divided into two groups: one receiving a daily supplement of 5,000 IU of vitamin E (E group), and the other receiving the same amount of vitamin E along with an additional 7g of vitamin C (E+C group). The supplementation period lasted for three weeks before the race.
• Data was collected at several points during the race, included blood samples, heart rate, and temperature taken the day before the race, during the race at 21 km and 56 km, at completion, and after 20 min of recovery.
• The researchers tested various elements in the plasma and in both red and white blood cells.

Results

• Out of the 46 horses, 34 completed the race and 12 did not finish due to various reasons including lameness, metabolic problems, and rider decisions.
• The E+C group showed higher plasma ascorbate (Vitamin C) levels compared to the E group.
• Neither antioxidant status nor creatine kinase (CK) and aspartate aminotransferase (AST) activities were affected by the addition of vitamin C to the antioxidant supplementation.
• Red blood cell glutathione peroxidase, white blood cell total glutathione, lipid hydroperoxides, CK, and AST all increased with distance, while red blood cell total glutathione and white blood cell glutathione peroxidase activity decreased with distance.
• There was a positive correlation between plasma lipid hydroperoxides, CK and AST, suggesting an association between muscle leakage and a cumulative index of oxidative stress.

Conclusion

• The study concluded that while the antioxidant supplementation may increase the plasma ascorbate status of the horses, it did not significantly influence their antioxidant status or muscle enzymes.
• Furthermore, it was observed that oxidative stress indices and muscle leakage were related and both increased with the distance of the ride. This implies that endurance races can lead to increased oxidative stress in horses, regardless of antioxidant supplementation.