Effects of the Feeding Rate of High Protein Calf Milk Replacers

Weaning and postweaning reductions in ADG in calves fed large amounts of milk or milk replacers (MR) are common. The purpose of these trials was to determine the effect of feeding a high CP MR at different rates on ADG, starter intake, and efficiency. In trial 1, a 26% CP, 17% fat MR was fed at either 0.681 kg/ d (P681), and then stepped up to 0.794 kg/d by d 8 (P794), or stepped up to 0.908 kg/d by d 15 (P908). In trial 2, P681 and P908 were fed. In trial 3, calves were fed either P681, 26% CP, 17% fat MR stepped up to 1.135 kg/d by d 22 (P1135), 28% CP, 20% fat MR stepped up to 1.135 kg/d by d 22 (PF1135), or conventional 20% CP, 20% fat MR at 0.454 kg/d (C454). Calves fed P794, P908, P1135, and PF1135 had faster ADG from 0 to 21 d and less starter intake from 0 to 56 d compared with calves fed P681 (P < 0.05); however, ADG from 0 to 56 d did not differ. In trials 2 and 3, efficiency for 0 to 21 d was better in calves fed P908, P1135, and PF1135, but worse vs. P681 (P < 0.05) after d 42. The ADG of calves fed P681 was faster than calves fed C454 (P < 0.05), but starter intake did not differ. The maximum amount of a high CP MR that could be fed without creating a weaning and postweaning slump in performance was 0.681 kg/d.