Selenium is important in this respect as it is a vital component of selenoenzymes (e.g. glutathione peroxidase) which play a role in reducing ROS and therefore maintain antioxidant status. A continuous optimal selenium supply is difficult to maintain as uptake from the diet will be impaired when high stress (e.g. sickness) is present. At that moment selenium is in high demand, for the production of selenoenzymes, and a storage inside the animal would be beneficial.
Maintaining an optimal selenium status – A nutritional solution
Selenium can be added to the diet in either inorganic or organic forms. The advantage of using organic selenium (L-Selenomethionine) over inorganic sources (e.g. sodium selenite or selenate) is its ability to be incorporated directly into animal proteins. This incorporated selenium acts as a storage depot of selenium inside the animal. L-Selenomethionine is the only selenium compound that can be directly, without conversion, built into animal structural proteins (e.g. muscle and liver). This ensures optimal selenium supply, even during stressful periods when it is in high demand by the animal L-Selenomethionine has traditionally been supplied to the diet via addition of selenised yeast. However, the yeast approach is limited. Normally, around 63% of the total selenium in a selenised yeast is present as L-Selenomethionine but there is a huge variation between products and batches. The percentage of selenium present as L-Selenomethionine can be as low as 18%! The remaining selenium absorbed by the yeast cells is present in forms that are no more active than much cheaper inorganic selenium. The introduction of Excential Selenium 4000 (Orffa, The Netherlands) into the market now provides a superior option to optimally supply animals with L-Selenomethionine.