Dairy calf growth performance when fed a modified accelerated milk replacer program

Our previous studies demonstrated that a modified accelerated milk replacer (MR) having a 24:20 CP:fat concentration fed at higher feeding rates (FR) resulted in improved growth performance and G:F, but the result was not linear. The objective of the current study was to evaluate preweaning (d 1 to 42) and postweaning (d 43 to 56) calf performance when a modified accelerated MR was fed at greater FR compared with a MR having similar or greater CP and lower fat concentrations. A total of 126 (2 to 5 d old) Holstein heifer calves (40.1 ± 0.76 kg) were blocked by birthdate and randomly assigned to 1 of 5 treatments. Treatments of MR fed at 14.7% solids were (1) control (C−): all milk 24:20 MR fed at 0.26 kg at 2×/d from d 1 to 35; (2) C+: C− MR fed at 0.32 kg 2×/d from d 1 to 35; (3) LF: CP and low fat (24:16) MR fed at 0.32 kg 2×/d from d 1 to 35; (4) LF+: LF MR fed at 0.32 kg 2×/d from d 1 to 7 and at 0.39 kg from d 8 to 35; and (5) HP+: high CP:LF MR (26:16) using the same FR as LF+. All MR were fed 1×/d from d 36 to weaning at d 42 with water and 18% CP texturized calf starter offered free choice at all times. Calves fed C+ had greater (P < 0.05) ADG (0.71, 0.75, 0.70, 0.72, and 0.72 kg/d for C−, C+, LF, LF+, and HP+, respectively) from d 1 to 56 compared with calves fed LF, with other treatments being intermediate. Calves fed C+, LF, and HP+ were similar but taller at the hips (P < 0.05) than calves fed LF+ (98.4, 99.6, 99.8, 98.1, and 99.8 cm), whereas calves fed C+ tended (P < 0.10) to have greater hip widths at 84 d (26.2, 26.5, 26.0, 26.2, 26.4 cm) than calves fed LF. This study demonstrates that feeding a modified accelerated MR (24:20) at a moderate FR improves ADG and frame measurements for calves fed MR having similar or different CP and fat concentrations. The development of a modified accelerated feeding program optimized the protein-to-energy ratio for producing a dairy heifer with a frame that is taller and wider, without having a postweaning BW gain slump.