Grains contain a natural source of organic selenium, but the grains grown in the tri-state area have a low selenium content. Although inorganic selenium (sodium selenite) is approved by FDA and is routinely added to most swine diets at 0.3 ppm, research has shown that about 60% of it is excreted in the urine. Organic selenium (yeast) is an effective source of selenium; is more effectively retained in muscle, milk, and fetal tissues than inorganic selenium; and less is excreted. Currently, the organic yeast product is not approved by FDA.