Age of calf at weaning of spring-calving beef cows and the effect on cow and calf performance and production economics

Over a 5-yr period, spring-calving cows were used in a carry-over design ex periment to evaluate effects of calf age at weaning on cow and calf perform ance and production economics. Weaning management groups were early (n = 60 , calf age 150 d, EW), traditional (n = 60, calf age 210 d, NW), and late ( n = 60, calf age 270 d, LW). Cow body condition score (BCS) and weights at the last weaning date were different (P < .05) for EW (5.8, 583 kg), NW (5. 5, 560 kg), and LW (5.2, 541 kg) management groups. Pregnancy rates among g roups were similar. Days on feed for groups differed (P = .001) and was 247 for EW, 204 for NW, and 164 d for LW steers. Average daily gain in the fee dlot differed (P = .01) among groups and averaged 1.5 kg for LW, 1.4 kg for NW, and 1.3 kg for EW steers. Dry matter intake while steers were in the f eedlot was greater (P = .001) for LW than for NW and EW calves. Hot carcass weight was greater (P = .01) for EW (328 kg) and NW (332 kg) calves than f or LW (321 kg) steers, and fat depth was greater (P = .05) for EW and NW st eers than for LW steers. When carcass data for the NW and LW steers were ad justed to the fat depth of EW steers, carcass characteristics among groups were similar. Net income per steer at slaughter for the feedlot phase was g reater (P < .001) for the EW ($75.36) and NW ($62.16) steers than for the L W ($10.09) steers. Again, when carcass data for the NW and LW steers were a djusted to the same fat depth of the EW steers, net income differences amon g groups were reduced. Replacement heifers were developed in a drylot and c osts were higher (P < .001) for the EW than for NW and LW heifers. Annual c ow costs were greater (P < .10) for the LW ($443.45) than for the EW ($410. 09) and NW ($421.35) groups. Break-even for each system on a steer financia l basis was not different between the NW and LW groups, and both the NW and LW groups had lower (P = .08) break-evens than the EW group. Age of the ca lf at weaning affects cow weight and BCS. Net income in each system is infl uenced by cow costs, month of the year that steer calves are purchased into the feedlot and finished steers are sold, month of the year cull cows are marketed, and replacement heifer development costs.