Effects of calf age at weaning on cow and calf performance and feed utilization in an intensive production system

Abstract Text: This research compared the feed utilization of producing a weaned calf to 205 d of age between early and normal weaning in an intensive production system.  Multiparous, crossbred (Red Angus x Red Poll x Tarentaise x South Devon x Devon), lactating beef cows (n = 84) with summer-born calves at side were blocked by prebreeding BW (H, M, L), stratified by calf age, and randomly assigned to 1 of 4 treatments within strata.  The experiment was a randomized complete block design with a 2 x 2 factorial arrangement of treatments with three replications.  Cow-calf pairs at 1 of 2 locations in eastern (ARDC) or western (PHREC) Nebraska were weaned at 90 (EW) or 205 (NW) d of calf age.  Regardless of location, EW cows and calves and NW pairs were fed a common diet (60:40 distillers grains:crop residue, DM) from the time of early to normal weaning.  EW cows were limit-fed (6.8 kg DM/cow/d) while EW calves were fed ad libitum.  NW pairs were limit-fed the equivalent amount of DM consumed by EW cows and calves.  All cattle were managed in earthen feedlot pens, and pen was the experimental unit.  Cow BW and BCS at early weaning were similar (P = 0.56) between EW and NW cows.  At normal weaning, EW cows had greater (P = 0.05) BW than NW cows.  Body weight change from early to normal weaning was 21 kg greater (P ≤ 0.01) for EW than NW.  Cow BCS at normal weaning was not impacted (P = 0.23) by weaning regimen or location.  Calf BW at early weaning was not different (P = 0.85) between EW or NW calves.  EW calves gained 10 kg less than NW from early to normal weaning.  EW cows and calves consumed 10.7 kg DM total/d while NW pairs consumed 10.3 kg DM/pair/d and performance between treatments was similar implying comparable feed utilization.  Data suggest weaned cows and calves require the same amount of feed as pairs together, and early-weaning does not reduce the feed energy needed to support the pair.

Keywords: cow-calf pairs, feed utilization, production system