In Trial 1, 108 crossbred steer calves (initial BW 295 kg) were allotted to 12 pens and used in a 186-d feedlot trial to determine the effects of increasing or decreasing roughage level on feedlot performance and carcass characteristics. Four dietary treatments were investigated: 1) 85% concentrate diet fed for 186 d, 2) 100% concentrate diet fed for 186 d, 3) 85% concentrate diet fed for 84 d followed by a 100% concentrate diet for the remaining 102 d, and 4) 100% concentrate diet for 84 d followed by an 85% concentrate diet for the remaining 102 d. Corn silage was added as roughage. During the first 84 d, level of dietary concentrate did not affect (P > .10) ADG. Steers switched to the 85% concentrate diet for the last 102 d had higher (P < .05) DMI than those fed the 100% concentrate diet; they did not exhibit an increase in ADG. Finishing phase feed efficiency was highest (P < .05) for steers continually fed 100% concentrate, lowest (P < .05) for steers continually fed 85% concentrate, and intermediate for steers whose concentrate level was switched during the trial. Carcass characteristics were not affected (P > .10) by concentrate level regimen. In Trial 2, 108 crossbred steer calves (initial BW 319 kg) were allotted to 12 pens and used in a 158-d trial to determine whether feedlot performance could be enhanced by manipulating roughage level and grain processing. Factors investigated were staged increases in concentrate level (70 to 85 to 100%) vs staged decreases in concentrate level (100 to 85 to 70%) and whole vs rolled high-moisture corn. Corn silage was added as roughage. Diet concentrate levels were changed on d 56 and 112. During the first 56 d, steers fed 70% concentrate diets grew 11% faster (P < .05) and consumed 19% more feed (P < .05) than those fed 100% concentrate diets. Steers fed rolled corn gained 8% faster (P < .06) and were 7% more efficient (P < .06) than those fed whole corn. During the last period (d 113 to 158), ADG was not affected (P > .10) by concentrate level or corn processing. Although increasing roughage during the feeding period increased feed intake in these trials, steer performance was not enhanced. Processing high-moisture corn did not affect feedlot performance.
All Science Journal Classification (ASJC) codes
- Food Science
- Animal Science and Zoology