Efficacy of feeding selenium-enriched yeast to finishing beef cattle

An experiment was conducted to evaluate supplementation with Se yeast of a finishing diet containing adequate Se from feedstuffs. Forty calves (307 ± 3.2 kg) were blocked by sex and randomly allotted to 8 pens. After completing acclimation to the diet, pens were randomly assigned within sex to the basal finishing diet (CON) or the basal finishing diet plus 0.34 mg of supplemental Se per kilogram of dietary DM from Se yeast (SUP) for a 130-d finishing period. Body weight and blood samples were obtained at 28-d intervals and before shipping. At slaughter, hot carcass weights were recorded and liver samples collected. After a 48-h chill, standard carcass data and LM samples were obtained. No differences (P > 0.10) in BW, ADG, DMI, feed efficiency, or any carcass measures were detected. Serum Se had a treatment-bytime interaction (P < 0.01) where initial serum Se concentrations were similar, but subsequently SUP calves had greater (P < 0.01) serum Se concentrations than did CON calves. Muscle and liver Se concentrations were lower (P < 0.01) for CON than for SUP calves. There was a treatment-by-sex interaction (P < 0.01), with heifers on SUP having higher liver Se concentrations than those of SUP steers. Results of this experiment indicate that supplementing 0.34 mg/kg Se (DM) from Se yeast to a basal feedlot diet with adequate Se does not increase performance but does result in increased tissue Se concentrations that do not exceed a range determined as normal.