Effects of Time on Feed and Postmortem Aging on Palatability and Lipid Composition of Crossbred Wagyu Beef

Twenty-seven Wagyu-sired steers were fed for 90 (14 steers) or 170 (13 steers) days to study the effects of time on feed on palatability and fatty acid composition, and the effects of post-mortem aging time (2, 4 or 10 days) on palatability. Hot carcass weight, fat thickness, longissimus dorsi muscle area, yield grade, estimated kidney, pelvic and heart fat and maturity score were increased (p \u3c 0.05) by an additional 80 days on the high concentrate feed, but marbling was not changed (p \u3e 0.05). Feeding the high concentrate diet for 170 days increased Warner-Bratzler shear force values (p \u3c 0.05) and tended to decrease tenderness (p \u3e 0.05), flavor intensity and connective tissue scores. For the 90 day feeding group, 4 days of aging improved connective tissue score (p \u3c 0.05) and tended to increase (p \u3e 0.05) tenderness scores and decrease shear force, compared with 2 days of aging. For the 170 day feeding group, 10 days of aging improved (p \u3c 0.05) shear force and all sensory attributes except flavor intensity, compared to 2 days of aging. An additional 80 days on feed decreased (p \u3c 0.05) stearic acid and total saturated fatty acids (SFA) and generally increased (p \u3c 0.05) monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), MUFA:SFA, and PUFA:SFA in subcutaneous fat and longissimus dorsi muscle. The cholesterol content of fat and muscle increased (p \u3c 0.05) as time on feed increased. Ninety days on a high concentrate diet was adequate for yearling crossbred Wagyu steers to produce highly acceptable carcasses. The additional 80 days on feed produced little or no overall benefit and the steers became overfinished and less tender. Ten days post-mortem aging improved (p \u3c 0.05) all palatability attributes except flavor intensity