Effects of Weaning Date and Retained Ownership on Cow and Calf Performance and Forage Disappearance in Spring Calving Beef Systems

Weaning calves early from spring calving cows can have multiple impacts on beef production systems. The objective of this three-state study was to evaluate the effects of mid-August (AW) versus early-November weaning (NW) on cow and calf production traits and forage utilization. Three hundred-seventeen cow-calf pairs from the NDSU- Dickinson Research Extension Center (DREC; n=88), SDSU-Antelope Research Station (ANT; n=136) and the University of Wyoming Beef Unit (UW; n=93) were stratified by BW and body condition score (BCS) and assigned to either AW (calves weaned at approx. 140 d of age) or NW (calves weaned at approx. 215 d of age). Cows grazed native range between the two weaning dates. At AW date, a subset of cows from each treatment at DREC were randomly assigned to six 20-ha. pastures (three pastures/treatment) to measure biomass disappearance between AW and NW dates. Steer calves at ANT and DREC were weaned and backgrounded 7.3 wk and finished in a commercial feed yard. Steers at UW were backgrounded 42 d and finished on site. Treatment by location interactions were detected for cow BW change, BCS change, calf ADG, and gain:feed. At each location, AW cows lost less weight (P<0.01) between weaning dates than NW cows. Similarly, cow BCS change was improved (P<0.01) for AW vs. NW at DREC (0.39 and -1.20), ANT (0.34 and -0.02), and UW (-0.05 and -0.78). Forage biomass disappearance, between weaning dates, was reduced by 27.7% (P=0.15) when calves were AW. AW steers at DREC had higher (P<0.01) ADG during backgrounding than NW, and AW steers at DREC and ANT were more efficient (P<.01) during backgrounding. During finishing, AW steers grew slower (P<.01), were less efficient (P<.01) at ANT, and overall were 31 days younger, but required 61 more days on feed to reach harvest endpoint. Weaning spring-born calves at 140 d compared to 215 d reduced forage utilization, improved cow BCS change, and resulted in similar calf performance.