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Under normal circumstances, substances called antioxidants thwart much of the wreckage caused by free radicals. However, oxidation speeds up during athletic effort due to increased oxygen consumption and accelerated aerobic metabolism.
In instances of strenuous exercise, natural stores of antioxidants have difficulty providing sufficient protection against the cascade of free radicals generated from aerobic metabolism. Supplementation of antioxidants is therefore necessary to help ward off the ill effects of mass-produced free radicals associated with intense exercise. Horses with an inadequate reserve of antioxidants may experience muscle soreness or stiffness during an exercise bout and prolonged recovery following hard work.
The All-Star Antioxidants
Vitamin E contributes most generously to the natural antioxidant defenses of the horse. The term vitamin E is actually a collective one that encompasses eight distinctive compounds of plant origin.
These eight are divided into four tocopherols and four tocotrienols. Of these only two--alpha-tocopherol and gamma-tocopherol--have antioxidant properties, and alpha-tocopherol is the most biologically active. On the cellular level, alpha-tocopherol embeds in cell membranes and protects cells from the ravages of free radicals. Alpha-tocopherol has an affinity for fat and is therefore attracted to cell membranes, which are composed of polyunsaturated fatty acids.
Feeds typically fed to horses have variable vitamin E concentrations. Cereal grains such as corn, oats, and barley contain minimal vitamin E, and processing may further decrease vitamin activity. Drying corn artificially, for example, reduces the alpha-tocopherol level by as much as 50%. And while vegetable and soybean oils possess substantially more vitamin E than grains, refining can diminish content. Even if they undergo only minimal refining, these oils have such low inclusion rates in diets that their contribution to total vitamin E intake is miniscule...
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