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Antioxidant supplementation and subsequent oxidative stress of horses during an 80-km endurance race¹

C. A. Williams^*,2, D. S. Kronfeld, T. M. Hess, K. E. Saker, J. N. Waldron, K. M. Crandell, R. M. Hoffman and P. A. Harris^¶

^* Department of Animal Science, Rutgers—The State University of New Jersey, Cook College, New Brunswick 08901; and Department of Animal and Poultry Science, Virginia PolytechnicInstitute and State University, Blacksburg 24061; and Virginia-Maryland Regional Collegeof Veterinary Medicine, Blacksburg, VA 24061; and Rectortown Equine Clinic, Rectortown, VA 20118; and and ^¶ Equine Studies Group, Waltham Centre for Pet Nutrition, Melton Mowbray, U.K.

² Correspondence: Cook Campus, 84 Lipman Dr. (phone: 732-932-5529; fax: 732-932-6996; e-mail: cwilliams{at}aesop.rutgers.edu).

Abstract

This study tested the development of oxidative stress and the effects of antioxidant supplementation in an 80-km ride. A precompetition survey revealed that no competitor would participate without vitamin E supplementation; therefore, 46 horses were paired for past performances and randomly assigned to two groups of 23 each for 3 wk of supplementation before the ride. One group (E) was orally supplemented with 5,000 IU of vitamin E per day; the other group (E+C) received that dose of vitamin E plus 7 g/d of vitamin C. Blood samples, temperature, and heart rate were taken the day before the race, at 21 and 56 km during the ride, at completion, and after 20 min of recovery. Plasma was assayed for lipid hydroperoxides, -tocopherol, total ascorbate, albumin, creatine kinase (CK), and aspartate aminotransferase (AST). Total glutathione and glutathione peroxidase activity were determined in red blood cells and white blood cells. Thirty-four horses completed the race, 12 horses (six in E and six in E+C) did not finish for reasons including lameness, metabolic problems, and rider option. Plasma ascorbate was higher (P = 0.045) in the E+C group than in the E group. Other than ascorbate, neither antioxidant status nor CK and AST activities were affected by supplementation with E+C vs. E. Red blood cell glutathione peroxidase, white blood cell total glutathione, lipid hydroperoxides, CK, and AST increased, and red blood cell total glutathione and white blood cell glutathione peroxidase activity decreased with distance (P < 0.001). Positive correlations were found for plasma lipid hydroperoxides on CK (r = 0.25; P = 0.001) and AST (r = 0.33; P < 0.001). These results establish an association between muscle leakage and a cumulative index of oxidative stress.

Key Words: -Tocopherol • Ascorbate • Endurance Exercise • Equine • Muscle Enzymes • Oxidative Stress

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				C. A. Williams, M. E. Gordon, C. L. Betros, and K. H. McKeever Apoptosis and antioxidant status are influenced by age and exercise training in horses J Anim Sci, March 1, 2008; 86(3): 576 - 583. [Abstract] [Full Text] [PDF]