University of Arkansas, Fayetteville Division of Agriculture
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Abstract

Selenium (Se) is deficient in many Arkansas soils; therefore, an experiment was conducted on steers to evaluate the effects of two supplemental Se sources on performance, blood metabolites, and immune function. Thirty Angus-crossbred steers were blocked by weight and assigned within block to one of 15 pens (two steers/pen). Pens were assigned randomly within blocks to one of three dietary treatments consisting of a corn-soybean meal supplement devoid of supplemental Se (negative control, NC) or corn-soybean meal supplements providing 1.7 mg supplemental Se/d as sodium selenite (inorganic Se, ISe) or as Se yeast (organic Se, OSe). Steers were offered fescue hay to allow for approximately 10% refusals, and 1.1 kg/d (as fed basis) of the appropriate grain supplement. Level and source of supplemental Se did not affect average daily gain for the 105-d trial. By d 42, steers fed both sources of supplemental Se had greater blood Se concentrations than those fed the NC. On d 63 and 84, blood Se concentrations differed among all dietary treatments (NC < ISe < OSe), and on d 105 steers fed both sources of supplemental Se had greater blood Se concentrations than NC. Antibody response to vaccination for bovine respiratory viruses, or in vitro lymphocyte blastogenesis did not differ among steers fed the different diets. Both sources of supplemental Se increased blood Se concentrations, the organic source more rapidly than the inorganic source; however, Se level and source had minimal effects on immune function of weaned beef steers.

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