Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 20, 2009
Publication Date: March 20, 2010
Citation: King, D.A., Shackelford, S.D., Kuehn, L.A., Kemp, C.M., Rodriguez, A.B., Thallman, R.M., Wheeler, T.L. 2010. Contribution of Genetic Influences to Animal-to-Animal Variation in Myoglobin Content and Beef Lean Color Stability. Journal of Animal Science. 88:1160-1167. Interpretive Summary: Anecdotal evidence from the beef industry suggests that muscles from some animals do not possess adequate color-stability to satisfy requirements for case-ready packaging programs. However, knowledge regarding the extent and source of animal-to-animal variation in steak color stability is limited. This research utilized a population of cattle representing seven widely used beef breeds to evaluate the genetic contributions to lean color stability of ribeye steaks. Large variation existed in steak color and steak color stability. After 6 days of simulated retail display, steak color traits, including color stability, were moderately heritable. Breed differences were found in steak color variables at the end of retail display. Charolais and Limousin carcasses produced steaks with greater color stability than steaks from Angus, Hereford, and Red Angus carcasses. These findings suggest that genetic influences contribute to animal-to-animal variation in steak color, particularly in maintaining steak color. Thus, it may be possible to select for enhanced steak color stability resulting in increased profitability due to decreased discounts at the retail store.
Technical Abstract: Longissimus thoracis steaks from steers (n = 464) with 0 to 50% inheritance of Angus (A), Charolais (C), Gelbvieh (G), Hereford (H), Limousin (L), Red Angus (RA), and Simmental (S) were evaluated during 6 d of display to assess genetic contributions to color stability. Color space values (CIE L* [lightness], a* [redness], b* [yellowness]), chroma, color change (delta E), and surface metmyoglobin (K/S 572/525) were determined on d 0 and 6. Myoglobin concentration was highly heritable (0.85), but ultimate pH was lowly heritable (0.06). Day 0 L* values were moderately heritable (0.24). Variation in metmyoglobin, L*, and delta E on d 6 was moderately explained by genetic factors (41, 40, and 29%, respectively). Change during display was moderately heritable for a* (0.31), b* (0.23), chroma (0.35), and surface metmyoglobin (0.29). At the start of display, A- steaks had higher (P < 0.05) L* values than those from all other breeds except C. On d 6, A- steaks had higher (P < 0.05) L* (50.0) values than G-, H-, and S- steaks (46.1, 44.0, and 44.5, respectively). Day 0 values for a*, b*, chroma, and delta E were not affected by breed (P > 0.05). On d 6, a* values were higher (P < 0.05) for C- and L- steaks (31.1 and 30.5) than A-, H-, and RA- steaks (27.4, 27.7, and 26.3, respectively). Thus, a* changed less (P < 0.05) in C- and L- steaks (1.8 and 2.6, respectively) versus steaks from all other breeds. Day 6 b* values were higher (P < 0.05) in C- (24.5) and L- (24.0) steaks versus G- (22.2), H- (21.9), and RA- (21.4) steaks. Thus, b* values changed less (P < 0.05) in C- and L- steaks (1.5 and 1.7, respectively) than in A-, G-, H-, and RA- steaks (4.3, 3.8, 4.4, and 5.1, respectively). After 6 d of display, C- and L- steaks had higher chroma (P < 0.05; 39.5 and 38.8, respectively) compared to A-, H-, and RA- steaks (35.4, 35.3, and 33.9, respectively). Less (P < 0.05) change in chroma occurred for C- and L- (2.1 and 2.8, respectively) than in A-, G-, H-, and RA- steaks (7.1, 6.6, 7.4, and 9.0, respectively). Myoglobin concentration was lower for C- and L- (P < 0.05; 2.77 and 2.72, respectively) compared to G-, RA-, and S- steaks (3.62, 3.43, and 3.71, respectively). Breeds did not differ in pH. These data suggest C- and L- carcasses produce steaks with greater lean color stability than A-, H-, and RA- carcasses. Furthermore, these findings suggest that genetics contribute substantially to animal-to-animal variation in lean color, particularly in maintaining color.