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This Article Full Text Full Text (PDF) All Versions of this Article: jas.2007-0201v1 86/1/205    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Gruber, S. L. Articles by Platter, W. J. Search for Related Content PubMed PubMed Citation Articles by Gruber, S. L. Articles by Platter, W. J.

Effects of ractopamine supplementation and postmortem aging on longissimus muscle palatability of beef steers differing in biological type

S. L. Gruber^*, J. D. Tatum^*,1, T. E. Engle^*, K. J. Prusa, S. B. Laudert, A. L. Schroeder and W. J. Platter

^* Department of Animal Sciences, Colorado State University, Fort Collins 80523-1171; and Department of Food Science and Human Nutrition, Iowa State University, Ames, 50011; and and Elanco Animal Health, Greenfield, IN 46140

¹ Corresponding author: J.Daryl.Tatum{at}Colostate.edu

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.

Key Words: aging • beef • biological type • palatability • ractopamine • tenderness