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Vitamin D (D3) supplementation may be used to increase tenderness in beef from cattle fed zilpaterol hydrochloride (ZH). The study was arranged as a 2 × 2 factorial with fixed effects of ZH (no ZH or ZH fed at 8.3 mg/kg DM for 20 d with a 3-d withdrawal) and D3 (no D3 or 500,000 IU D3·steer·d for 10 d prior to harvest). Cattle ( = 466) were harvested in 2 blocks on the basis of BW with subsequent collection of carcass data. Full loins and inside rounds ( = 144 of each subprimal) were collected for fabrication of 5 steaks from the longissimus lumborum (LL), gluteus medius (GM), and semimembranosus (SM), which were aged for 7, 14, 21, 28, or 35 d. Warner-Bratzler shear force (WBSF) was used to evaluate mechanical tenderness of LL, GM, and SM steaks at all aging periods. Slice shear force (SSF) analysis was conducted on only 14- and 21-d LL steaks. No interactions ( > 0.05) between ZH and D3 occurred throughout the entire study. Supplementing ZH resulted in increased HCW ( 0.05) on WBSF or SSF of LL steaks. Like for WBSF, ZH supplementation increased SSF values at 14 and 21 d postmortem ( 0.05) on WBSF values of GM steaks. Feeding ZH did not alter WBSF of SM steaks, but at 28 d D3 increased ( = 0.04) WBSF values. Shear force in ZH steaks was not effectively reduced by feeding D3 for 10 d to steers prior to harvest. Aging, however, was an effective method of reducing initially greater shear force values in LL steaks and, to a lesser degree, GM steaks from ZH-fed cattle.

An experiment was conducted to determine the effects of zilpaterol hydrochloride mM supplementation (ZH; 8.3 mg/kg on a DM basis for 20 d) and calcium chloride injection [CaCl(2), 200 at 5% (wt/wt) at 72 h postmortem] on palatability traits of beef (Bos taurus) strip loin steaks. Select (USDA) strip loins were obtained from control (no ZH = 19) and ZH-supplemented carcasses (n = 20). Right and left sides were selected alternatively to serve as a control (no INJ) or CaCl(2)-injected (INJ) and stored at 4°C. Before injecting the subprimals (72 h postmortem), 2 steaks were cut for proximate, sarcomere length, and myofibrillar fragmentation index (MFI) analyses. At 7 d postmortem each strip loin was portioned into steaks, vacuum packaged, and aged for the appropriate period for Warner-Bratzler shear force (WBSF; 7, 14, 21, and 28 d postmortem), trained sensory analysis (14 and 21 d postmortem), purge loss (7 d), and MFI (3, 7, 14, 21, and 28 d postmortem). Results indicated steaks from both ZH supplementation and INJ had reduced WBSF values as days of postmortem aging increased. The WBSF values of ZH steaks were greater (P0.05) than no ZH steaks at each postmortem aging period. The INJ steaks had lower WBSF values (P0.05) than non-injected steaks. A greater percentage (91 vs. 71%) of steaks had WBSF values4.6 kg from steers with no ZH supplementation at 7 d postmortem, but the percentage did not differ (P0.05) due to ZH at 14, 21, or 28 d or due to INJ at any aging period. Trained panelists rated tenderness less in ZH steaks than steaks with no ZH at 14 d and 21 d. However, INJ improved (P0.05) the tenderness ratings and flavor intensity of the trained panelists, compared with their non-injected cohorts at 21 d. Zilpaterol hydrochloride supplementation reduced (P0.05) MFI values, but INJ resulted in greater (P0.05) MFI values compared with no INJ. Subprimals from ZH and INJ showed greater purge loss (P0.05). Although no interactions were found with ZH and CaCl(2), injecting USDA Select strip loins from ZH-fed cattle can help reduce the normal WBSF variation as it does in steaks from non-ZH-fed cattle.

Our objectives were to determine the effects of zilpaterol hydrochloride (ZH) and the release rate of trenbolone acetate and estradiol-17β on the Warner-Bratzler shear force (WBSF) and slice shear force (SSF) of longissimus lumborum (LL) and the WBSF of gluteus medius (GM) and psoas major (PM) in response to various aging periods. British × Continental steers (n = 168) were assigned to treatments in a 3 × 2 factorial. The main effects of treatment were implant (no implant, Revalor-S, Revalor-XS, Intervet/Schering Plough Animal Health, De Soto, KS) and ZH (0 or 8.3 mg/kg of DM for 20 d). Slaughter group was included as a random effect to account for the variation in days on feed (153 or 174 d). Loins (n = 96) were fabricated to obtain strip loin, top sirloin butt, and tenderloin subprimals. Five 2.54-cm steaks were cut from each subprimal and assigned to 1 of 5 aging periods (7, 14, 21, 28, or 35 d postmortem). Feeding ZH increased (P ≤ 0.01) LL WBSF and SSF values at each aging period compared with controls. Implanting increased (P0.05) LL WBSF values at 14 and 21 d, but did not affect LL SSF values (P0.05). Only Revalor-S increased (P ≤ 0.05) WBSF values at 28 and 35 d compared with no implant or Revalor-XS. The percentage of LL steaks with a WBSF value below 4.6 kg did not differ (P0.05) between ZH supplementation or implant strategy at any aging period, and by d 28, more than 99% of LL steaks registered WBSF values below 4.6 kg. Feeding ZH increased (P0.05) GM WBSF values only on d 21. Implant had no effect (P0.05) on GM WBSF values. The percentage of GM steaks with a WBSF value below 4.6 kg did not differ (P0.05) between ZH supplementation or implant strategy at any aging period. Neither ZH nor implant strategy affected PM WBSF values (P0.05). All PM WBSF values were below 4.6 kg on d 7. The results of this study indicated that feeding ZH increased WBSF and SSF of LL steaks, regardless of the aging period; however, the percentage of steaks with WBSF below 4.6 kg did not differ because of ZH or implant. Implanting increased LL WBSF values, but not SSF values. These results showed that although differences existed between implanting, as well as ZH supplementation of British × Continental steers, 99% of LL steaks were classified as tender based on WBSF values by extending aging to 28 d postmortem. It should be noted that 21.2% of 7-d, 13.8% of 14-d, and 17.3% of 21-d ZH steaks had WBSF values greater than 4.6 kg, but 0% of nonsupplemented steaks were greater than 4.6 kg at these aging periods. However, because ZH and implants can increase retail yield of valuable subprimals, such as the tenderloin, considerable value could be captured through ZH supplementation with anabolic implants because shear force was not affected in PM steaks.