title: Effects of synthetic hormone implants, singularly or in combinations, on performance, carcass traits, and longissimus muscle palatability of Holstein steers.
abstract: Seventy-two Holstein steers averaging 182 kg were assigned randomly to one of six treatment groups: 1) nonimplanted controls (C); 2) implanted with 36 mg of zeranol (Z); 3) implanted with 20 mg of estradiol benzoate and 200 mg of progesterone (EP); 4) implanted with 140 mg of trenbolone acetate (TBA); 5) implanted with 140 mg of trenbolone acetate plus 20 mg of estradiol benzoate and 200 mg of progesterone (TBA + EP); and 6) implanted with 140 mg of trenbolone acetate plus 36 mg of zeranol (TBA + Z). Each treatment group consisted of three replications of four animals per pen, which were implanted on d 0, 56, 112, and 168. Masculinity and muscling scores were assigned at 24 h preslaughter. Hide removal difficulty was scored by a plant supervisor. Quality and yield grade data were obtained at 24 h postmortem. Longissimus muscle (LM) steaks were removed and cooked for Warner-Bratzler shear (WBS) determinations and sensory panel (SP) evaluations. Over the entire feeding period (249 d), TBA + EP steers had higher (P less than .05) ADG than TBA + Z, TBA, and C steers. All treatments had higher (P less than .05) ADG than C, with the exception of TBA. The only feed efficiency differences were those following the 168-d implant time, when TBA steers were more (P less than .05) efficient than TBA + Z or C steers. The TBA + EP and TBA + Z steers were more (P less than .05) masculine and their hides were more (P less than .05) difficult to remove than those of EP and C steers. Carcass weights of TBA + EP steers were heavier (P less than .05) than those of TBA or C steers. The TBA + EP steers had larger (P less than .05) LM areas than Z, TBA, and C steers. Also, TBA + EP steers tended (P = .07) to have lower numerical yield grades than EP, Z, or C steers. Even though mean marbling scores and quality grades were similar (P greater than .05) among treatment groups, only 50% of TBA + EP carcasses graded low Choice or higher, compared with 100, 75, 82, 90, and 83% for C, TBA, Z, EP, and TBA + Z carcasses, respectively. The only meat palatability differences were that myofibrillar and overall tenderness scores tended to be lower (P = .07) for steaks from EP and TBA + Z than for steaks from Z and C groups.
authors.affiliation: Anim. Sci. and Ind. Dept., Kansas State University, Manhattan 66506.
authors.forename: J K
authors.initials: JK
authors.lastname: Apple
authors.forename: M E
authors.initials: ME
authors.lastname: Dikeman
authors.forename: D D
authors.initials: DD
authors.lastname: Simms
authors.forename: G
authors.initials: G
authors.lastname: Kuhl
mesh_terms: D045930:Anabolic Agents / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D002417:Cattle / Q000033:anatomy & histology / Q000254:growth & development*; D004338:Drug Combinations; D004343:Drug Implants; D004435:Eating / Q000187:drug effects; D004958:Estradiol / Q000008:administration & dosage / Q000494:pharmacology; D006728:Hormones / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008460:Meat / Q000592:standards*; D009132:Muscles / Q000187:drug effects*; D011374:Progesterone / Q000008:administration & dosage / Q000494:pharmacology; D014204:Trenbolone Acetate / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D015430:Weight Gain / Q000187:drug effects; D015029:Zeranol / Q000008:administration & dosage / Q000494:pharmacology
chemical_list: D045930:Anabolic Agents; D004338:Drug Combinations; D004343:Drug Implants; D006728:Hormones; D011374:Progesterone; D004958:Estradiol; D015029:Zeranol; D014204:Trenbolone Acetate