Growth performance of newborn dairy calves fed a milk replacer containing 24% crude protein and 20% fat fed at different feeding rates

Objective: The objective was to evaluate the preweaning (d 1 to 42) and postweaning (d 43 to 56) performance and health of calves fed a 24% CP:20% fat milk replacer (MR) at different feeding rates based on our previous work that calves fed greater feeding rates of MR demonstrated improved growth. Materials and Methods: A total of 108 (2- to 5-d-old) Holstein heifer calves (40 ± 0.69 kg) were randomly assigned to 1 of 4 treatments. The same all-milk-protein MR was fed at 14.7% solids, with treatments of (1) control (MR57): MR fed at 0.57 kg daily from d 1 to 35; (2) MR71: MR fed at 0.71 kg daily from d 1 to 35; (3) MR85: MR fed at 0.68 kg daily from d 1 to 7 and at 0.85 kg daily from d 8 to 35; and (4) MR99: MR fed at 0.68 kg daily from d 1 to 7 and at 0.99 kg daily from d 8 to 35. All treatments were fed MR one time per day from d 36 to weaning, after d 42 with water, and an 18% CP texturized calf starter offered free choice. Results and Discussion: Preweaning and overall ADG (0.78, 0.82, 0.83, and 0.85 kg/d for MR57, MR71, MR85, and MR99, respectively) were greater (P < 0.10) for calves fed MR99 compared with calves fed MR57 with other calves being similar (P > 0.10) and intermediate. Overall d 1 to 56 calf starter intakes were greater (P < 0.05) for calves fed MR57 compared with calves fed MR85 and MR99, whereas total DMI was similar (P > 0.10). Preweaning G:F was lowest for calves fed MR57, whereas d 1 to 56 G:F (0.49, 0.52, 0.52, and 0.54 kg/kg of DM) was greater (P < 0.05) for calves fed MR99 compared with calves fed MR57, with other calves being intermediate. Implications and Applications: This study demonstrated that higher feeding rate of a 24:20 MR resulted in increased ADG and feed conversion (G:F).