Selenium is an essential nutrient at 0.1 parts per million for almost all livestock species. Many studies have indicated the rate of growth and health of animals and poultry is improved when selenium is added to feeds at 0.3 parts per million. However, selenium can be toxic at high levels, with an LD50 (lethal dose for 50% of test animals) of about 7 parts per million (7 grams per metric tonne). Microtracers manufactures a number of selenium products, using sand and iron as carriers instead of coarse limestone. Our selenium products are also treated with hydrogenated soybean oil to reduce dustiness.


  • Dispersion – Microtracers selenium products disperse well in feed premixes and final feeds
  • Less dusty – 90% less dusty than limestone based selenium sources, a worker safety issue
  • Flows well – Products are presifted so they flow well in materials handling equipment, a major problem as as selenium compounds are hygroscopic and may accumulate in premix conveying equipment and may then release into premixes at toxic levels


Sodium Selenite Content 10%
Particle Count 100/mg
Particle Size Avg. 150 microns, no larger than 750 microns
Color Off-white to dark-tan
Packaging Grey plastic pails meeting UN specifications
Expiration Date 3 years


SDS – Microtracers 4.5% Selenium on Sand

Product Data Sheet – Microtracers 4.5% Selenium on Sand

“Relative Stability of Selenites and Selenates in Feed Premixes as a Function of Water Activity “, Dr. Sylvan Eisenberg et al, Journal of AOAC International, Vol. 90, No. 2, March 2007, P 349-353.

”Selenium Addition to Feeds”, David Eisenberg, Zootechnica International, July/August 1993.