Department of Animal and Food Science, Texas Tech University, Lubbock 79409, USA.
J Anim Sci. 2011 Nov;89(11):3783-91. doi: 10.2527/jas.2011-4134. Epub 2011 Jun 16.
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 (P < 0.05) LL WBSF values at 14 and 21 d, but did not affect LL SSF values (P > 0.05). 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 (P > 0.05) 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 (P < 0.05) GM WBSF values only on d 21. Implant had no effect (P > 0.05) on GM WBSF values. The percentage of GM steaks with a WBSF value below 4.6 kg did not differ (P > 0.05) between ZH supplementation or implant strategy at any aging period. Neither ZH nor implant strategy affected PM WBSF values (P > 0.05). 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.
我们的目标是确定盐酸齐帕特罗（ZH）和醋酸去甲雄三烯醇酮和雌二醇-17β的释放速率对背最长肌（LL）的 Warner-Bratzler 剪切力（WBSF）和切片剪切力（SSF）以及臀中肌（GM）和腰大肌（PM）的 WBSF 的影响，这些因素会随着不同的老化期而变化。英国×大陆牛（n = 168）被分配到 3×2 的处理因素中。处理的主要影响因素是植入物（无植入物、Revalor-S、Revalor-XS、Intervet/Schering Plough Animal Health、De Soto、KS）和 ZH（0 或 8.3mg/kg DM 饲喂 20d）。屠宰组作为随机效应，以解释饲料天数（153 或 174d）的变化。获得带里脊肉、上臀肉和里脊副产物的里脊肉。从每个副产物中切出 5 个 2.54cm 的牛排，并将其分配到 5 个不同的老化期（死后 7、14、21、28 或 35d）之一。与对照组相比，饲喂 ZH 增加了（P≤0.01）LL WBSF 和 SSF 值在每个老化期。植入物增加（P<0.05）14 和 21d 的 LL WBSF 值，但不影响 LL SSF 值（P>0.05）。只有 Revalor-S 增加了（P≤0.05）28 和 35d 的 WBSF 值，而无植入物或 Revalor-XS 则没有。在任何老化期，ZH 补充或植入策略都不会影响（P>0.05）LL 牛排的 WBSF 值低于 4.6kg 的百分比，并且到第 28d 时，超过 99%的 LL 牛排的 WBSF 值低于 4.6kg。饲喂 ZH 仅增加了（P<0.05）GM 的 WBSF 值在第 21d。植入物对 GM 的 WBSF 值没有影响（P>0.05）。在任何老化期，ZH 补充或植入策略都不会影响（P>0.05）GM 牛排的 WBSF 值低于 4.6kg 的百分比。ZH 或植入策略都不会影响 PM 的 WBSF 值（P>0.05）。所有 PM 的 WBSF 值在第 7d 时都低于 4.6kg。这项研究的结果表明，饲喂 ZH 增加了 LL 牛排的 WBSF 和 SSF，无论老化期如何；然而，由于 ZH 或植入物，WBSF 值低于 4.6kg 的牛排的比例没有差异。植入物增加了 LL 的 WBSF 值，但不增加 SSF 值。这些结果表明，尽管在植入物和英国×大陆牛的 ZH 补充之间存在差异，但通过将老化期延长至死后 28d，99%的 LL 牛排根据 WBSF 值被归类为嫩牛排。应该注意的是，7d 的 21.2%、14d 的 13.8%和 21d 的 17.3%的 ZH 牛排的 WBSF 值大于 4.6kg，但在这些老化期，无补充的牛排的 WBSF 值没有大于 4.6kg 的。然而，由于 ZH 和植入物可以增加有价值的副产物（如里脊）的零售产量，因此通过 ZH 补充合成代谢植入物可以获得相当大的价值，因为 PM 牛排的剪切力不受影响。
