J. P. Schoonmaker, S.C. Loerch1,
F. L. Fluharty, T. B. Turner,
S. J. Moeller, and J. E. Rossi
The Ohio State University Department of Animal Sciences
Sixty-three calves were allotted to a bull or a steer group based on sire, birth date, and birth weight. At 75 days of age (5-15-98), calves in the steer group were castrated. Calves were not creep fed prior to weaning. All calves were weaned and weighed at an average age of 115 days of age (6-24-98) and transported by truck to the Ohio Agricultural Research and Development Center (OARDC) feedlot in Wooster, Ohio. Performance information and carcass characteristics were measured in three phases. Phase 1 was from 6-25-98 to 9-17-98; Phase 2 was from 9-18-98 to 12-3-98; Phase 3 was from 12-4-99 to harvest. Calves averaged 115, 200, and 277 days of age on 6-25-98, 9-17-98, and 12-3-98, respectively. Before implantation, four bulls and four steers were selected for serial slaughter and carcass evaluation. Steers were implanted with Synovex C at 130 days of age (7-9-98), Revalor S at 200 days of age (9-17-98), and Revalor S at 277 days of age (12-3-98). Bulls gained 9.7% faster (3.86 vs. 3.52 lbs/day; P < 0.01), consumed 56 more lbs. of DM (1,149 vs. 1,093 lbs.; P = 0.11), and were 3.3% more efficient (0.282 vs. 0.273 lb/lb, P < 0.10) than steers in Phase 1. However, steers gained 10.5% faster (3.57 vs. 3.23 lbs/day; P < 0.02), consumed similar amounts of DM and were 6.5% more efficient than bulls (0.214 vs. 0.201 lb/lb; P < 0.06) in Phase 2. Overall, gains and efficiency were similar between bulls and steers; however, bulls had to consume 309 more lbs of DM (P < 0.05), gain 59 more lbs of weight (P < 0.05), increase hip height growth 12.8% (P < 0.07), increase REA 12.3% (P < 0.03), and had to stay in the feedlot 18 more days (P < 0.05) than steers to achieve a similar amount of backfat. Eighty-five percent of both bulls and steers graded low choice or better. Placing early-weaned bulls and implanted steers on a high grain diet resulted in excellent feedlot performance and carcass characteristics in cattle marketed before a year of age.
1 For more information, contact at: The Ohio State University, Ohio Agricultural Research and Development Center, 1680 Madison Avenue, Wooster OH 44691, 303-263-3900, e-mail: loerch.1@osu.edu