:::: Merit Research Journals :::::::

In many parts of the world, soil is depleted of selenium (Se), resulting in selenium-poor plants, animals and, therefore, humans. It was recognized that a study to examine the functionality of new products on the market to address this problem was required. Selenium is recognized as an essential trace element and its deficiency in ruminants can result in numerous deficiency symptoms. According to Edens (2002) there are two sources of Se with which to supplement animal diets, an inorganic source and an organically bound source. Inorganic Se is available mostly in the form of Sodium selenite (Na Se), while organically bound Se is most common as selenides yeast in the form of selenomethionine. According to Mahan (1999) Na Se has a lower bioavailability in the rumen and some of the consumed Se is utilized by microorganisms for their metabolism. Organically bound Se instead can by-pass the rumen as it is in the form of selenoamino acids. The main advances in Se status assessment and Se requirements were established based on the activity of glutathione peroxidase (GSH-PX), an enzyme which for many years was considered to be the main selenoprotein. Recently it was discovered that it is only one of at least 25 various selenoproteins. Se research and practical applications are developing quickly and they are very exciting and promising in this papers, an attempt has been made to review effects the different Se sources on growth, Se bioavailability and the quality and lipid oxidation of muscle in the Lambs.

Keywords: Dietary Trace Mineral, Se bioavailability, milk yield, Performance, Reproductive and Immunity