Effects of corn processing, dietary roughage level, and timing of roughage inclusion on performance of feedlot steers.

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.