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

Abstract Text: A two-year experiment compared the feed utilization of producing a weaned calf to 205 d of age between early and normal weaning in an intensive beef cow-calf production system.  Multiparous, crossbred (Red Angus x Red Poll x Tarentaise x South Devon x Devon), lactating beef cows (n = 163) with summer-born calves at side were blocked by prebreeding BW (H, M, L), 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 x 2 factorial arrangement of treatments with three replications (pens) per treatment per year (total n = 24).  Treatment factors were: 1) location; eastern (ARDC) or western (PHREC) Nebraska and 2) calf age at weaning; 91 ± 18 (EW) or 203 ± 16 (NW) d of age.  Regardless of location, EW cows and calves and NW pairs were fed a common diet (60:40 distillers grains:crop residue [yr 1]; 40:40:20 corn silage:distillers grains:crop residue [yr 2], DM basis) from the time of early to normal weaning.  EW cows were limit-fed (6.9 kg DM/cow daily) while EW calves were offered ad libitum access to feed (4.0 kg DM/calf daily).  NW pairs were limit-fed the equivalent amount of DM consumed by EW cows and calves (10.8 kg/pair daily).  All cattle were managed in earthen feedlot pens, with pen serving as the experimental unit.  By design, BW and BCS at early weaning were similar (P ≥ 0.27) between EW and NW cows.  At normal weaning time, EW cows had greater BW than NW cows, and BW change from early to normal weaning was 17 kg greater (P ≤ 0.01).  Cow BCS at normal weaning time was not impacted (P = 0.42) by weaning management.  Likewise, calf age at weaning had no impact on BCS change.  As intended, calf BW at the time of early weaning was not different, but remained similar (P= 0.38) at normal weaning time.  NW and EW calves gained 0.85 and 0.82 kg daily, respectively.  Similar feed energy intake resulted in comparable performance between weaning regimens.  These data indicate early-weaning has minimal effect on reducing the feed energy needed to maintain a cow-calf pair.  Thus, decisions regarding early weaning should be made on the basis of management rather than feed efficiency. 

Keywords: cow, efficiency, weaning