In the August 25, 1997 Federal Register (FR), FDA published a final rule which adopted, without change, the provisions of an interim rule published in the FR of October 17, 1995 (60 FR 53702) regarding the approved use of selenium as a food additive in animal feeds. The current selenium food additive regulation (Title 21, Part 573.920 in the Code of Federal Regulations) provides for the use of sodium selenate or sodium selenite as sources of selenium for selenium supplementation of complete feeds for chickens, swine, turkeys, sheep, cattle, and ducks at a maximum level of 0.3 part per million (ppm); in feed supplements for limit feeding of sheep not to exceed an intake of 0.7 milligram (mg) per head per day and in beef cattle not to exceed an intake of 3 mg per head per day; in salt-mineral mixtures for free-choice feeding for sheep at levels up to 90 ppm at a rate not to exceed an intake of 0.7 mg per head per day and for beef cattle at levels up to 120 ppm at a rate not to exceed an intake of 3 mg per head per day. In addition, an osmotic selenium bolus may also be used as a source of selenium for beef and dairy cattle. The bolus provides 3 mg of selenium per day.