Table 1: Effect of calf age at weaning on cow body condition score (Bolte et al., 2007)
aBody condition score (scale = 1 to 9; 1 = emaciated, 9 = obese)
bInitial BCS was measured 60 d before calves were shipped to feedlot (d -60 weaning)
cFinal BCS was measured 60 d after calves were shipped to feedlot
In addition, the removal of calves from pastures reduces daily forage demands on the pasture. Nursing calves (100-150 days of age) are capable of consuming 1.5 to 2.0% of their bodyweight in dry forage per day. Thus a 450 lb calf is capable of consuming approximately 7 lbs of dry forage per day. A dry 1400 lb cow consumes approximately 28 lbs of dry forage per day (2% of bodyweight). If we divide the 28 lbs of forage needed to maintain the cow by the 7 lbs of forage spared by removing the calf; for every 4 days that a calf is not grazing, one additional grazing day for the cow is gained. Alternatively, for every 30 days a calf is weaned and removed from the pasture, one week (7.5 grazing days) is gained to support the cow.
Cattle producers often express concerns regarding the performance potential and ability of early weaned calves to utilize feedstuffs in dry lot environments. However, early weaned calves ranging in age from 113 to 144 days in studies conducted at K-state have gained in excess of 2.0 lb/day with feed conversions ranging from 4.0 to 5.0 Feed:Gain (Bailey et al.,2013; Preedy et al., 2014). If managed appropriately and provided adequate nutrition, early weaned calves perform well and often exhibit a tremendous capacity for feed conversion. Additionally, early weaned calves may be managed to target value-added calf sales or preconditioning programs.
Early weaning is a herd management practice that can be implemented to manage the nutrient demands associated with lactation, reduce forage demands on pastures, and improve cow condition and market-ready calves if managed appropriately.