Gruber S L, Tatum J D, Engle T E, Prusa K J, Laudert S B, Schroeder A L, Platter W J
Department of Animal Sciences, Colorado State University, Fort Collins 80523-1171, USA.
J Anim Sci. 2008 Jan;86(1):205-10. doi: 10.2527/jas.2007-0201. Epub 2007 Sep 18.
Effects of ractopamine hydrochloride (RAC) supplementation and postmortem aging on palatability of beef from steers differing in biological type were evaluated using LM samples from British, Continental crossbred, and Brahman crossbred calf-fed steers (n = 98/type). Equal numbers of steers within each type were assigned to treatments of 0 or 200 mg.steer(-1).d(-1) of RAC fed during the final 28 d of the finishing period. Warner-Bratzler shear force (WBSF) was measured at 3, 7, 14, and 21 d postmortem, and trained sensory panel (TP) evaluation was conducted using LM samples aged for 14 d postmortem. A RAC x type interaction (P = 0.006) was detected for WBSF. Within each type, steers fed RAC produced steaks with greater (P < 0.05) WBSF values than steaks from control steers; however, the magnitude of the effect of RAC on WBSF was more pronounced among Brahman cross-breds (5.53 vs. 4.96 +/- 0.10 kg) than among Continental crossbred (4.16 vs. 3.96 +/- 0.10 kg) and British steers (4.10 vs. 3.75 +/- 0.10 kg). The effect of RAC on WBSF, though diminished slightly by aging (mean WBSF difference: 3 d = 0.49 kg; 21 d = 0.24 kg), was not completely mitigated by 21 d of postmortem storage (P(RAC x AGE) = 0.16). Steers fed RAC produced steaks that received lower (P < 0.05) TP ratings for tenderness (8.09 vs. 8.95 +/- 0.18) and juiciness (7.41 vs. 8.07 +/- 0.16 kg), along with slightly lower (P = 0.06) ratings for beef flavor (6.67 vs. 6.93 +/- 0.10 kg), compared with steaks from unsupplemented steers, regardless of biological type. Among the 3 biological types, Brahman crossbred cattle produced steaks with the greatest (P < 0.05) WBSF values at each aging period; WBSF values for steaks from British and Continental type steers did not differ (P > 0.05) at any aging time. Sensory panel ratings of tenderness, juiciness, and beef flavor were greatest (P < 0.05) for steaks from British steers, and least (P < 0.05) for steaks produced by Brahman-type steers. Results from this study suggest that RAC supplementation slightly decreases LM tenderness (WBSF and TP) of British, Continental crossbred, and Brahman cross-bred steers, and that the effect of RAC on WBSF may be more pronounced in steaks from Brahman crossbred cattle than among stenks from Continental type or British steers.
使用来自英国、大陆杂交和婆罗门杂交犊牛育肥阉牛（n = 98/类型）的腰大肌样本，评估盐酸莱克多巴胺（RAC）添加和宰后成熟对不同生物学类型阉牛肉适口性的影响。每种类型中数量相等的阉牛被分配到在育肥期最后28天饲喂0或200 mg·阉牛⁻¹·天⁻¹ RAC的处理组。在宰后3、7、14和21天测量沃纳 - 布拉茨勒剪切力（WBSF），并使用宰后14天成熟的腰大肌样本进行训练有素的感官小组（TP）评估。检测到WBSF存在RAC×类型交互作用（P = 0.006）。在每种类型中，饲喂RAC的阉牛所产牛排的WBSF值高于对照阉牛所产牛排（P < 0.05）；然而，RAC对WBSF的影响程度在婆罗门杂交牛中（5.53对4.96±0.10 kg）比在大陆杂交牛（4.16对3.96±0.10 kg）和英国阉牛（4.10对3.75±0.10 kg）中更明显。RAC对WBSF的影响虽因成熟而略有减弱（平均WBSF差异：3天 = 0.49 kg；21天 = 0.24 kg），但在宰后储存21天时并未完全消除（P（RAC×AGE） = 0.16）。与未添加RAC的阉牛所产牛排相比，无论生物学类型如何，饲喂RAC的阉牛所产牛排的嫩度（8.09对8.95±0.18）和多汁性（7.41对8.07±0.16 kg）的TP评分较低（P < 0.05），牛肉风味评分也略低（P = 0.06）（6.67对6.93±0.10 kg）。在这3种生物学类型中，婆罗门杂交牛在每个成熟阶段所产牛排的WBSF值最高（P < 0.05）；英国和大陆类型阉牛所产牛排的WBSF值在任何成熟时间均无差异（P > 0.05）。英国阉牛所产牛排的嫩度、多汁性和牛肉风味的感官小组评分最高（P < 0.05），婆罗门类型阉牛所产牛排的评分最低（P < 0.05）。本研究结果表明，添加RAC会略微降低英国、大陆杂交和婆罗门杂交阉牛腰大肌的嫩度（WBSF和TP），并且RAC对WBSF的影响在婆罗门杂交牛所产牛排中可能比在大陆类型或英国阉牛所产牛排中更明显。
