title: Bioavailability of copper from copper glycinate in steers fed high dietary sulfur and molybdenum.
abstract: Sixty Angus (n = 29) and Angus-Sim-mental cross (n = 31) steers, averaging 9 mo of age and 277 kg of initial BW, were used in a 148-d study to determine the bioavailability of copper glycinate (CuGly) relative to feed-grade copper sulfate (CuSO(4)) when supplemented to diets high in S and Mo. Steers were blocked by weight within breed and randomly assigned to 1 of 5 treatments: 1) control (no supplemental Cu), 2) 5 mg of Cu/kg of DM from CuSO(4), 3) 10 mg of Cu/kg of DM from CuSO(4), 4) 5 mg of Cu/kg of DM from CuGly, and 5) 10 mg of Cu/kg of DM from CuGly. Steers were individually fed a corn silage-based diet (analyzed 8.2 mg of Cu/kg of DM), and supplemented with 2 mg of Mo/kg of diet DM and 0.15% S for 120 d (phase 1). Steers were then supplemented with 6 mg of Mo/kg of diet DM and 0.15% S for an additional 28 d (phase 2). Average daily gain and G:F were improved by Cu supplementation regardless of source (P = 0.01). Final ceruloplasmin, plasma Cu, and liver Cu values were greater (P < 0.05) in steers fed supplemental Cu compared with controls. Plasma Cu, liver Cu, and ceruloplasmin values were greater (P < 0.05) in steers supplemented with 10 mg of Cu/kg of DM vs. those supplemented with 5 mg of Cu/kg of DM. Based on multiple linear regression of final plasma Cu, liver Cu, and ceruloplasmin values on dietary Cu intake in phase 1 (2 mg of Mo/kg of DM), bioavailability of Cu from CuGly relative to CuSO(4) (100%) was 140 (P = 0.10), 131 (P = 0.12), and 140% (P = 0.01), respectively. Relative bio-availability of Cu from CuGly was greater than from CuSO(4) (P = 0.01; 144, 150, and 157%, based on plasma Cu, liver Cu, and ceruloplasmin, respectively) after supplementation of 6 mg of Mo/kg of DM for 28 d. Results of this study suggest that Cu from CuGly may be more available than CuSO(4) when supplemented to diets high in S and Mo.
authors.affiliation: Department of Animal Science, North Carolina State University, Raleigh 27695, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Hansen
authors.forename: P
authors.initials: P
authors.lastname: Schlegel
authors.forename: L R
authors.initials: LR
authors.lastname: Legleiter
authors.forename: K E
authors.initials: KE
authors.lastname: Lloyd
authors.forename: J W
authors.initials: JW
authors.lastname: Spears
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001682:Biological Availability; D002417:Cattle; D003300:Copper / Q000493:pharmacokinetics*; D004032:Diet / Q000662:veterinary; D019587:Dietary Supplements; D004305:Dose-Response Relationship, Drug; D005998:Glycine / Q000493:pharmacokinetics*; D008297:Male; D008982:Molybdenum / Q000494:pharmacology*; D009942:Organometallic Compounds / Q000493:pharmacokinetics*; D013455:Sulfur / Q000494:pharmacology*
chemical_list: D009942:Organometallic Compounds; C018493:cupric glycinate; D013455:Sulfur; D003300:Copper; D008982:Molybdenum; D005998:Glycine