ANN 111: Principles of Animal Nutrition and Feed Technology (2+1)

FUNCTIONS

• Vitamin E functions in the animal mainly as biological antioxidant
• In association with the selenium-containing enzyme glutathione peroxidase, it protects cells against oxidative damage caused by free radicals.
• Free radicals are formed during cellular metabolism and, as they are capable of damaging cell membranes, enzymes and cell nuclear material, they must be converted into less reactive substances if the animal is to survive.
• This protection is particularly important in preventing oxidation of polyunsaturated fatty acids. Oxidation of unsaturated fatty acids produces hydroperoxides, which also damage cell tissues and more lipid free radicals so that prevention of such oxidation is of vital importance in maintaining the health of the living animal.
• The animal has two main methods of protecting itself against oxidative damage. Firstly, radicals are scavenged by vitamin E as a first line of defence and secondly, glutathione peroxidase destroys any peroxide formed before they can damage the cell.
• These two defence mechanisms complement one another.
• Vitamin E also plays an important role in the development and function of the immune system.