Selenium Supplementation of Naturally High Selenium Diets for Swine

Two trials were conducted (one at Michigan State University and a second at South Dakota State University) involving supplementation of naturally high selenium swine diets (0.24 to 0.45 ppm) with 0.1 ppm of selenium from sodium selenite. In one trial, a low selenium diet (0.04 ppm) was supplemented with 0.40 ppm of selenium from sodium selenite to supply total selenium levels comparable to a naturally high selenium diet. Sodium selenite additions to the naturally high selenium diets did not significantly increase longissimus muscle or kidney selenium concentrations and increased liver selenium concentrations only slightly. Tissue selenium levels resulting from adding 0.40 ppm of selenium from sodium selenite to a naturally low selenium diet (0.04 ppm) were significantly lower than when a naturally high selenium diet (0.44 ppm) was fed. It appears that the dietary level of naturally-occurring organic selenium compounds is much more significant in influencing the tissue selenium concentration of the pig than supplemental selenium from sodium selenite.