The influence of diet and time on feed on carcass traits and quality

Seventy-two Simmental-sired steer calves (approximately 8 months old) were randomly assigned to one of two pre-finishing dietary treatments (low energy or high energy). Energy intake was monitored to produce average daily gains of approximately 0·41 (low energy) or 0·68 (high energy) kg during a 6-month growth interval. At 14 months of age the steers were assigned to four finishing (time on feed) groups-0, 56, 112 or 168 days. Steers assigned to the 0-day group received their respective pre-finishing diets from 14 to 20 months of age. The other groups received a finishing diet for the final 56, 112 or 168 days of the experiment. All steers were slaughtered at 20 months. Steers backgrounded on high energy diets produced heavier (P < 0·01), fatter (P < 0·01) carcasses with higher (P < 0·01) marbling scores and quality grades and LD steaks with greater (P < 0·05) ease of fragmentation, less (P < 0·05) detectable connective tissue and higher (P < 0·05) tenderness ratings as compared to steers on low energy diets. After 112 days on feed, quality grades were similar for high energy and low energy steers; however, tenderness ratings still favored the high energy treatment. Increased time on feed was associated with higher quality grades, but only within the low energy treatment group. Additionally, tenderness of LD steaks improved with increased time on feed; howver, the greatest improvement was observed from 0 to 56 days.