Selenium is a component of the enzyme glutathione peroxidase which serves to protect cellular tissues and membranes against oxidation. Selenium and vitamin E function synergistically. Sources of selenium include blood meal, corn gluten meal, fish solubles, fish meal, rapeseed meal and yeast. Selenium may be supplemented as sodium selenite. Recommended level of selenium in commercial feeds is 1 ppm (Akiyama et al., 1992).