title: Effects of supplement type and selenium source on measures of growth and selenium status in yearling beef steers.
abstract: Sugarcane molasses is a widely used animal feed by-product, but is concentrated in S (approximately 1%, DM basis) and has been shown to reduce the Cu status of cattle. Dietary S may also antagonize Se; therefore, two 90-d studies were conducted with forage-fed, yearling steers (12 pens; 2 steers/pen for each study) to investigate the impact of molasses supplementation on measures of Se status. In Exp. 1, steers were assigned isonitrogenous supplements with equivalent amounts of TDN from 2 sources (molasses or corn). Supplemental Se was provided (3.0 mg of Se/d; Na selenite) to both treatments. After 90 d of supplementation, steers provided corn diets had greater (P = 0.02) liver Se concentrations and tended (P = 0.07) to have greater ADG compared with steers supplemented with molasses. Irrespective of treatment (P >/= 0.54), plasma Se concentrations decreased (P < 0.001) and plasma glutathione peroxidase activity increased (P < 0.001) from d 0 to 90. In Exp. 2, sources of supplemental Se (2.5 mg/ d), fed within molasses supplements, were compared. Treatments included 1) Na selenite, 2) Se-yeast (Sel-Plex, Alltech, Nicholasville, KY), or 3) no Se (control). Cattle provided supplemental Se, irrespective of source, had greater (P </= 0.01) liver and plasma Se concentrations and greater (P </= 0.01) plasma glutathione peroxidase activity compared with control steers on d 60 and 90. Measures of Se status did not differ among steers supplemented with Na selenite and Se-yeast. These data suggest that dietary S, derived from sugarcane molasses, may antagonize liver tissue accumulation of Se in cattle. The Se status of cattle consuming sugar-cane molasses was similar when provided 2.5 mg of supplemental Se/d from Na selenite or Se-yeast sources.
authors.affiliation: Institute of Food and Agricultural Sciences, Range Cattle Research and Education Center, University of Florida, Ona 33865, USA. jarth@ufl.edu
authors.forename: J D
authors.initials: JD
authors.lastname: Arthington
mesh_terms: D000821:Animal Feed; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001682:Biological Availability; D002417:Cattle / Q000097:blood / Q000254:growth & development*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D005979:Glutathione Peroxidase / Q000378:metabolism*; D008297:Male; D008965:Molasses; D009752:Nutritional Status; D011897:Random Allocation; D012643:Selenium / Q000008:administration & dosage* / Q000097:blood* / Q000493:pharmacokinetics; D015430:Weight Gain; D003313:Zea mays
chemical_list: D005979:Glutathione Peroxidase; D012643:Selenium