title: Serum concentrations of trenbolone-17 beta and estradiol-17 beta and performance of heifers treated with trenbolone acetate, melengestrol acetate, or estradiol-17 beta.
abstract: The effects of the growth-promoting steroids estradiol-17 beta (E2), trenbolone acetate (TBA), and melengestrol acetate (MGA) in heifers on serum concentrations of E2 and trenbolone-17 beta (TBOH) were examined. Feed intake and growth performance were also measured. Serum concentrations of E2 and TBOH were measured on d 0, 1, 3, 5, 7, 13, 21, 28, 42, 56, 84, 112, and 140 in finishing heifers administered the following treatments: 1) control; 2) MGA, .5 mg per heifer daily; 3) Revalor-H (140 mg TBA + 14 mg E2); 4) Revalor-H + MGA; 5) Finaplix-H (200 mg TBA); and 6) Finaplix-H + MGA. Revalor-H implantation (Treatments 3 and 4) increased (P < .05) serum E2 concentrations; peak concentrations (67.5 pg/mL) occurred between d 21 and 56. Feeding MGA (Treatment 4) had no effect (P > .05) on this increase in serum E2 concentrations (63.3 pg/mL). From d 84 until d 140, serum E2 was greater (P < .05) for the Revalor-H treatment (average of 19 pg/mL) than for the control (7 pg/mL) or Finaplix-H treatments (6.5 pg/mL). Serum E2 concentrations increased numerically two- to threefold from d 56 to 140 in controls fed MGA, compared with controls not fed MGA. There was the expected increase in serum TBOH concentrations after TBA implantation in the Revalor-H and Finaplix-H treatments; concentrations were similar (P > .05) for Revalor-H (221 pg/mL) and Finaplix-H (280 pg/mL). After d 56, serum TBOH concentrations decreased in both treatments to 10 and 20% of these concentrations, respectively. Feeding MGA increased serum TBOH (P < .05). Dry matter intake by heifers did not differ among treatments. Feeding of MGA improved gains (P = .12) and efficiencies (P < .01) in nonimplanted heifers and had no effect (P > .4) on gains or efficiencies in Finaplix-implanted heifers.
authors.affiliation: Department of Animal and Veterinary Sciences, Clemson University, SC 29634, USA. DHNRCKS@Clemson.Edu
authors.forename: D M
authors.initials: DM
authors.lastname: Henricks
authors.forename: R T
authors.initials: RT
authors.lastname: Brandt
authors.forename: E C
authors.initials: EC
authors.lastname: Titgemeyer
authors.forename: C T
authors.initials: CT
authors.lastname: Milton
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D002417:Cattle / Q000097:blood* / Q000254:growth & development* / Q000276:immunology; D004338:Drug Combinations; D004343:Drug Implants; D004958:Estradiol / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology*; D005260:Female; D007106:Immune Sera / Q000276:immunology; D008552:Melengestrol Acetate / Q000008:administration & dosage / Q000494:pharmacology*; D045167:Progesterone Congeners / Q000008:administration & dosage / Q000494:pharmacology*; D011863:Radioimmunoassay / Q000379:methods / Q000662:veterinary; D011897:Random Allocation; D013997:Time Factors; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood* / Q000276:immunology / Q000494:pharmacology
chemical_list: D045930:Anabolic Agents; D004338:Drug Combinations; D004343:Drug Implants; D007106:Immune Sera; D045167:Progesterone Congeners; D004958:Estradiol; D008552:Melengestrol Acetate; D014204:Trenbolone Acetate