title: Anabolic implant effects on visceral organ mass, chemical body composition, and estimated energetic efficiency in cloned (genetically identical) beef steers.
abstract: Six sets of four genetically identical Brangus steers (n = 24; X BW 409 kg) were used to determine the effect of different anabolic implants on visceral organ mass, chemical body composition, estimated tissue deposition, and energetic efficiency. Steers within a clone set were randomly assigned to one of the following implant treatments: C, no implant; E, estrogenic; A, androgenic, or AE, androgenic + estrogenic. Steers were slaughtered 112 d after implanting; visceral organs were weighed and final body composition determined by mechanical grinding and chemical analysis of the empty body. Mass of the empty gastrointestinal tract (GIT) was reduced approximately 9% (P < .10) in steers implanted with estrogen alone or in combination with an androgen. Liver mass was increased (P < .10) from 6 to 14% by implants. Steers implanted with the AE combination had greater (P < .10) daily protein accretion (163.4 g/d) than either E (128.8 g/d) or A (137.1 g/d), and, because the combination improved gain above C (101.1 g/d), this demonstrates the additive effects of a combination implant on protein deposition. Anabolic implants did not alter (P > .10) the efficiency of ME utilization. In general, estrogenic implants decreased GIT, androgenic implants increased liver, and all implants increased hide mass. Steers implanted with an AE combination had additive effects on protein deposition compared with either implant alone. The NEg requirements for body gain are estimated to be reduced 19% by estrogenic or combination implants.
authors.affiliation: Department of Animal Sciences, Colorado State University, Fort Collins 80523, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Hutcheson
authors.forename: D E
authors.initials: DE
authors.lastname: Johnson
authors.forename: C L
authors.initials: CL
authors.lastname: Gerken
authors.forename: J B
authors.initials: JB
authors.lastname: Morgan
authors.forename: J D
authors.initials: JD
authors.lastname: Tatum
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000494:pharmacology*; D000728:Androgens / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001823:Body Composition / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D002417:Cattle / Q000235:genetics* / Q000254:growth & development / Q000502:physiology*; D019976:Cloning, Organism; D004064:Digestive System / Q000033:anatomy & histology / Q000187:drug effects; D004338:Drug Combinations; D004343:Drug Implants; D004734:Energy Metabolism / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D004967:Estrogens / Q000008:administration & dosage / Q000494:pharmacology; D006321:Heart / Q000033:anatomy & histology / Q000187:drug effects; D007668:Kidney / Q000033:anatomy & histology / Q000187:drug effects; D008099:Liver / Q000033:anatomy & histology / Q000187:drug effects; D008297:Male; D009929:Organ Size / Q000187:drug effects / Q000502:physiology; D013154:Spleen / Q000033:anatomy & histology / Q000187:drug effects; D014781:Viscera / Q000033:anatomy & histology / Q000187:drug effects*; D015430:Weight Gain / Q000187:drug effects / Q000502:physiology
chemical_list: D045930:Anabolic Agents; D000728:Androgens; D004338:Drug Combinations; D004343:Drug Implants; D004967:Estrogens