The Effect of Time on Feed on Certain Physical, Chemical and Sensory Traits of Forage- and Grain-Fed, Serially Slaughtered Angus Steers of Varying Yearling Frame Score Classification

Ninety-one steers grown on winter, spring and summer grass were randomly assigned, within frame size (small, medium or large), to six feeding treatments (pasture only or 28, 56, 84, 112 or 140 days on whole shelled corn fed ad libitum) so the effect of days on feed on certain production, carcass, cookery and chemical characteristics, and the effect of those preceding characteristics upon certain sensory and quantitative descriptors of beef loin steaks could be evaluated. The slaughter weights increased (P<.001) as days on feed (DOF) increased. Rib eye area and hot carcass weight also increased (P<.001) as DOF increased. Final mean yield and quality grades were 1.6, low standard; 1.8, high standard; 1.9, high good; 2.6, low choice; 2.8, average choice; and 2.4, average choice. Steers fed to 140 days had a higher dressing percentage (57.31%) than steers slaughtered straight off pasture (51.45%). Steers fed on whole shelled corn for 140 days were taller at the withers (P<.001), had a higher percentage of internal fat (P<.001) and revealed a higher degree of marbling (P<.001) than steers slaughtered immediately after the pasture stage. Sensory taste panelists rated loin steaks from the 140 day steers higher on tenderness (p<.001), juiciness (P<.001), flavor description (p<.001), flavor desirability (P<.001) and overall desirability (P<.001). Warner-Bratzler shear values declined (P<.01) for steaks from 140 day steers. Quantitative descriptive analysis panelists rated loin steaks from the 140 day steers to have a higher intensity of cooked beef fat flavor (P<.001) and a lower intensity of milky-oily flavor (P<.001). These data suggest that acceptable quality, yield grades and palatability can be obtained after 84 days of grain feeding.