Efficacy of dietary sodium selenite and calcium selenite provided in the diet at approved, marginally toxic, and toxic levels to growing swine.

A 2 x 3 factorial experiment conducted in three replicates of a randomized complete block design compared the effects of calcium selenite and sodium selenite at three different levels of Se (.3, 5, or 15 ppm) in the diets of growing swine on performance and tissue Se concentrations. Ninety pigs averaging 12.5 kg of BW were given ad libitum access to corn-soybean meal diets fortified with one of the treatment Se sources and dietary levels for a 35-d experimental period. Growth and feed intake were similar in pigs fed .3 and 5 ppm of Se but were lower (P less than .01) in those fed 15 ppm from either Se source. Serum Se increased (P less than .01) as dietary Se level increased with no difference between Se sources at each dietary Se level. Liver, kidney, and longissimus muscle Se concentrations increased (P less than .01) as the dietary level of Se increased and were similar when either Se sources was provided. These results indicate that calcium selenite was as effective as sodium selenite using the measurement criteria of growth, serum, and tissue Se concentrations and glutathione peroxidase activities of growing swine when fed at approved, marginally toxic, and toxic dietary Se levels.