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Title: Effects of frame size and animal age on beef carcass quality and tenderness

Author
item DUCKETT, S - Clemson University
item Neel, James
item LEWIS, R - Virginia Polytechnic Institution & State University
item SWECKER, W - Virginia Polytechnic Institution & State University
item FONTENOT, J - Virginia Polytechnic Institution & State University
item Clapham, William

Submitted to: American Society of Animal Science Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2010
Publication Date: 7/11/2010
Citation: Duckett, S.K., Neel, J.P., Lewis, R., Swecker, W., Fontenot, J.P., Clapham, W.M. 2010. Effects of frame size and animal age on beef carcass quality and tenderness. Journal of Animal Science, 88(Suppl 2):274.

Interpretive Summary:

Technical Abstract: Angus-cross steers (n = 96) were used to determine the effects of frame size (medium, MED or small, SM) and animal age on beef carcass quality and tenderness in a forage finishing system. Steers grazed mixed pastures (bluegrass/white clover) and were slaughtered at 16.6, 18.6, and 20.3 mo of age in a two-year study. At 24 h postmortem, carcass traits were collected and a rib from each carcass obtained for Warner-Bratzler shear force (WBSF) analysis. In year 1, postmortem aging treatments included 14 and 28 d. In year 2, postmortem aging treatments included 2, 4, 7, 14, and 28 d. Hot carcass weight, fat thickness, and skeletal maturity scores increased (P <0.05) with animal age. Marbling scores, quality grades, and yield grades were greater (P < 0.05) for 20.3 than 16.6 mo. Longissimus muscle color was lighter (P < 0.05) and less red (P < 0.05) in 16.6 than 20.3 mo. Subcutaneous fat color was lighter (P < 0.05) and yellower (P < 0.05) for older than younger carcasses. Hot carcass weight and ribeye area were greater (P < 0.05) for MED than SM. Frame size did not alter other carcass parameters. In both years, the interaction between animal age and postmortem aging was significant. In year 1, WBSF values at d 14 were lower, more tender (P < 0.05) for 16.6 mo than 18.6 and 20.3 mo. Extending the postmortem age to 28 d did not change (P > 0.05) WBSF values in young and intermediate ages but did improve tenderness (P < 0.05) for the older age group. In year 2, WBSF values were lower, more tender (P < 0.05) at d 2 of postmortem aging 16.6 mo than 18.6 or 20.3 mo. At 14 d postmortem, steaks from 16.6 and 18.6 mo were more tender (P < 0.05) than 20.3. By d 28, WBSF values did not differ (P > 0.05) among animal ages. In pasture-based beef finishing systems, increasing animal age results in larger carcasses with more external fat and marbling; however tenderness of ribeye steaks decreases with advanced age such that longer postmortem aging times are required to achieve similar tenderness level.