Evaluation of weaning strategies using an automated milk replacer feeder on growth performance and physiological responses in Hanwoo calves

초록

Objective: To assess automated feeder milk replacer (MR) weaning strategies for Hanwoo (Korean native cattle) calves and identify a cost-effective program that improves growth, feed efficiency, and timely adaptation to solid feed. Methods: Four 60-d MR programs were compared with a standard control by changing one key factor: MR feeding frequency (T1; 4 vs. 6 meals/d), MR solids concentration (T2; 13% vs. 15%), MR duration in the early feeding period (T3; 30 d vs. 37 d), or the MR tapering strategy in the late feeding period (T4; linear vs. step-down). Performance outcomes included dry matter intake (DMI), average daily gain (ADG), feed conversion ratio (FCR), and weaning body weight, and physiological responses were assessed with complete blood counts (CBCs) and serum biochemical profiles (SBPs). Results: Across treatments, performance differences were driven primarily by the MR-to-solid-feed transition method and timing rather than total DMI. In T1, MR DMI tended to be lower, and ADG was the lowest (p<0.001), which is consistent with reduced appetite under frequent MR meals. T2 increased MR DMI but yielded only moderate growth, with higher diarrhea incidence and duration and higher aspartate aminotransferase and lactate dehydrogenase, suggesting greater metabolic load at 15% vs. 13% MR solids. Compared with the control, T3 and T4 improved ADG and FCR, with significant treatment effects (p<0.001), and increased weaning body weight (p = 0.001). T3 prolonged MR-centered feeding early, whereas T4 used step-down tapering to increase solid feed intake late and promote earlier solid feed reliance. CBC and SBP showed no added disturbance in T3 or T4. Conclusion: Both T3 and T4 increased growth and efficiency. T4 performed comparably with reduced MR and earlier solid feed dependency, indicating practical and economic benefits.

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