title: Effects of zilpaterol hydrochloride and zilpaterol hydrochloride withdrawal time on beef carcass cutability, composition, and tenderness.
abstract: The impact of zilpaterol hydrochloride (ZH) on carcass yield, composition, and tenderness was evaluated using 384 beef steers in a randomized complete block design. Main effects were the addition of 0 or 8.3 mg/kg of ZH for the final 20 d of feeding and each inclusion level was paired with withdrawal periods of 3, 10, 17, or 24 d. The 2 animals with BW closest to the pen average were selected for carcass fabrication to determine carcass yield, composition, and tenderness. The carcasses from animals fed ZH had greater (P = 0.008) individual side weights. Carcass fat determinations were unchanged (P = 0.70) by ZH. Weights of the strip loin (P = 0.01), peeled tenderloin (P = 0.02), and top sirloin butt (P < 0.001) were all improved with ZH. When expressed as a proportion of carcass weight, ZH increased percentage of carcass in the top sirloin butt (P = 0.006), bottom sirloin tri-tip (P = 0.02), top inside round (P = 0.002), bottom round flat (P = 0.001), and flank steak (P = 0.02). A longer withdrawal time (WT) increased (P < 0.001) carcass weights. Shoulder clod weights were greatest (P < 0.001) with 17-d WT from ZH, whereas chuck roll weights were greatest (P = 0.02) at 17 and 24 d of WT. Peeled tenderloins, top sirloin butts, and eye of rounds responded to WT, with increased (P < 0.001) weights seen at 10 d of WT as compared with all other WT. Shear force values were greater at each of the 3 aging times, 7 d (P < 0.001), 14 d (P < 0.001), and 21 d (P = 0.003), in steaks from ZH-fed steers compared with control steers. Protein percentages were greater in ZH steaks (P = 0.03) and ZH ground beef trim (P < 0.001). Percent moisture was increased (P < 0.001) in strip loin steaks at 3 and 10 d WT. Ground beef trim had an increase (P = 0.04) in percent moisture and a decrease (P = 0.01) in percent fat at 10 d WT. Carcass weights and yields were improved with ZH feeding and may continue to improve even up to 10 d after withdrawal of the supplement. Tenderness was slightly reduced with ZH supplementation but was unaffected by WT. Zilpaterol hydrochloride can be a valuable supplement to finishing beef steers to improve carcass lean yields and composition.
authors.affiliation: Department of Animal Science, Oklahoma State University, Stillwater 74078, USA.
authors.forename: J N
authors.initials: JN
authors.lastname: Shook
authors.forename: D L
authors.initials: DL
authors.lastname: VanOverbeke
authors.forename: L A
authors.initials: LA
authors.lastname: Kinman
authors.forename: C R
authors.initials: CR
authors.lastname: Krehbiel
authors.forename: B P
authors.initials: BP
authors.lastname: Holland
authors.forename: M N
authors.initials: MN
authors.lastname: Streeter
authors.forename: D A
authors.initials: DA
authors.lastname: Yates
authors.forename: G G
authors.initials: GG
authors.lastname: Hilton
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005503:Food Additives / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008460:Meat / Q000592:standards*; D008462:Meat-Packing Industry; D013997:Time Factors; D014297:Trimethylsilyl Compounds / Q000008:administration & dosage / Q000494:pharmacology*; D015430:Weight Gain / Q000187:drug effects
chemical_list: D005503:Food Additives; D014297:Trimethylsilyl Compounds; C475840:Zilpaterol