title: Effect of a combined trenbolone acetate and estradiol implant on feedlot performance, carcass characteristics, and carcass composition of feedlot steers.
abstract: Objectives of this study were to determine the influence of trenbolone acetate (TBA) and estradiol (E2) in a combined implant on feedlot performance, carcass characteristics, and carcass composition in finishing steers. Sixty-four large-framed (394.1 kg) crossbred steers were randomly assigned to one of four pens. Subsequently, pens were randomly assigned to one of two treatments, implanted (120 mg of TBA and 24 mg of E2) and nonimplanted. Eight steers/treatment were slaughtered for initial carcass composition. Remaining steers were assigned to one of three serial slaughter dates (d 40, 115, or 143). Implantation increased circulating trenbolone (TBOH) and E2 concentrations throughout the trial. Implantation increased ADG 18% (P < .001) during d 0 to 40, 21% (P < .001) from d 0 to 115, and 16% for the entire 143 d. Implant status had no effect (P > .05) on dry matter intake. Feed efficiency was improved 13% during d 0 to 40 (P < .01) and from d 41 to 115 (P = .07). Longissimus muscle area was larger (P < .05) in implanted steers than in nonimplanted steers on d 115. Carcasses from implanted steers had a smaller (P < .05) percentage of kidney, pelvic, and heart (KPH) fat on d 143 than those from nonimplanted steers. Carcasses from implanted steers possessed more carcass protein (P < .05) on d 40. Implanted steers had an 82% increase (P < .05) in daily carcass protein accretion during the first 40 d. Implantation increased (P < .01) carcass water but did not affect carcass fat accumulation throughout the feeding period. The combined TBA+E2 implant improved feedlot performance and stimulated carcass protein accretion in feedlot steers.
authors.affiliation: Department of Animal Science, University of Minnesota, St. Paul 55108, USA.
authors.forename: B J
authors.initials: BJ
authors.lastname: Johnson
authors.forename: P T
authors.initials: PT
authors.lastname: Anderson
authors.forename: J C
authors.initials: JC
authors.lastname: Meiske
authors.forename: W R
authors.initials: WR
authors.lastname: Dayton
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D000821:Animal Feed / Q000592:standards; D000818:Animals; D001823:Body Composition / Q000187:drug effects*; D002417:Cattle / Q000254:growth & development*; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology*; D008297:Male; D008460:Meat / Q000592:standards*; D009124:Muscle Proteins / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects; D011863:Radioimmunoassay / Q000379:methods / Q000662:veterinary; D011897:Random Allocation; D013997:Time Factors; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology
chemical_list: D045930:Anabolic Agents; D004338:Drug Combinations; D004343:Drug Implants; D009124:Muscle Proteins; D004958:Estradiol; D014204:Trenbolone Acetate