Growth performance of Girolando and Guzolando calves under contrasting early-life management systems: a retrospective study in a tropical climate dairy farm

This retrospective study evaluated how two early-life management systems influenced calf growth and health in a dairy operation in Coclé, Panamá. The Individual Weaning Management (IWM) system housed calves in large groups (>10 animals) and weaned them individually, whereas the Group Weaning Management (GWM) system maintained smaller, consistent groups (~6 animals) with collective weaning. Data from 149 (Girolando, Guzolando, and crossbred) were analyzed. All calves received standardized nutrition, including milk replacer and concentrate provided at 10% of body weight. Body weights were recorded at birth and weaning, with longitudinal growth assessed in Girolando and Guzolando calves. Mixed-effects modeling identified birth weight, weaning age, and management system as significant predictors of weaning weight. Calves under GWM had significantly higher weaning weights (5.61 ± 1.77 kg; p = 0.0047). However, dietary differences, including the use of corn distillate in IWM, represent a potential confounder. Health outcomes also differed: diarrhea incidence was significantly lower in GWM calves (3.5%) compared with IWM (14.3%). Despite these early advantages, postweaning growth trajectories did not differ between systems (p = 0.867), suggesting compensatory growth in IWM calves. Overall, GWM improved early growth and health and may be preferable in settings with strong biosecurity and health monitoring protocols.