Effects of Concentrate- Versus Forage-Based Finishing Diet on Carcass Traits, Beef Palatability, and Color Stability in Longissimus Muscle from Angus Heifers

The objective was to determine the effects of finishing diet on carcass traits, beef palatability, and color stability of LM from Angus heifers. Half-siblings were obtained from a herd selected for increased intramuscular fat, ribeye area, and percentage of retail product, and decreased backfat and were randomly assigned to a forage- or concentratebased finishing diet. Longissimus muscle samples (n = 155) were obtained and fabricated into steaks for trained sensory panel, Warner-Bratzler shear force, thiobarbituric acid-reactive substances (TBARS), and simulated retail display evaluation. Data were analyzed using the MIXED procedures of SAS using slaughter age as a covariate. Carcasses from concentrate-finished heifers had greater adjusted fat thickness (1.86 vs. 0.87 cm), greater percentage of KPH (2.14 vs. 1.35%), greater numerical YG (3.38 vs. 2.25), and greater marbling scores (modest 90 vs. traces 70) than forage-finished heifers (P < 0.05). Steaks from concentrate- fed heifers had lesser Warner- Bratzler shear force values (3.67 vs. 5.05 kg), greater tenderness ratings, greater beef flavor intensity, lesser grassy/cowy flavor intensity, and greater painty/fishy flavor intensity than steaks from foragefed heifers (P < 0.05). Initial TBARS were greater (P < 0.05) in steaks from concentrate-fed heifers when compared with grass-fed heifers, but TBARS were not different (P > 0.05) between diets after 7 d in retail display. Of the color measurements, only L* values differed between diets; they were greater (38.36 vs. 32.25; P < 0.05) for steaks from concentrate-fed heifers. This study points to several differences in beef palatability resulting from finishing diet composition.