The effect of calf age at weaning on cow and calf performance and feed utilization by cow-calf pairs1

The effect of calf weaning age on cow and calf performance and feed utilization was investigated over 2 yr. Multiparous, crossbred, lactating beef cows (n = 156) with summer-born calves were blocked by prebreeding BW, stratified by calf age, and assigned randomly to 1 of 4 treatments within strata. The experiment was a randomized complete block design with a 2 × 2 factorial arrangement of treatments with 3 replications (pens) per treatment per year (total n = 24). Factors were (1) location-Agricultural Research and Development Center (ARDC) or Panhandle Research and Extension Center (PHREC)-and (2) calf weaning age-early weaned (EW) at 91 ± 18 d of age or conventionally weaned (CW) at 203 ± 16 d of age. All cows and calves were fed a common diet from early to conventional weaning time within each year and location. Cows with weaned calves were limit fed (6.9 kg of DM/cow daily), and EW calves were offered ad libitum access to feed (4.0 kg of DM/calf per day). Nursing pairs were fed an equivalent amount of DM (10.8 kg/ pair per day). Initial cow BW and BCS were similar (P ≥ 0.26), but BW change from early to conventional weaning was 17 kg greater (P ≤ 0.01) for EW cows. Cow BCS and conception rates were not affected (P ≥ 0.38) by weaning. Calf BW at conventional weaning was greater (P ≥ 0.05) for CW than EW at ARDC but greater (P ≥ 0.05) for EW than CW calves at PHREC. Calf ADG per unit of total feed energy intake was greater (P ≥ 0.05) for nursing pairs at ARDC but not different between EW and CW at PHREC, indicating early weaning may have minimal effect on reducing feed energy requirements.