Efecto de la edad de destete sobre el desempeño animal de terneras Hereford destetadas precozmente

The objective of this study was to evaluate the effect of weaning age on the productive performance of early-weaned Hereford heifer calves. The experiment was conducted at the Estación Experimental Dr. Mario A. Cassinoni (EEMAC), specifically at the Unidad de Producción Intensiva de Carne (UPIC), in Paysandú, Uruguay, during a 70-day period between February and April 2025. A total of 24 Hereford heifer calves were used and assigned to two treatments according to age at weaning: older calves (88 ± 12 days) and younger calves (56 ± 13 days), all with an average weight greater than 70 kg. The experiment was conducted under a completely randomized design with three replicates per treatment. It included an initial pen-adaptation (habituation) phase and an experimental grazing phase on a pasture composed of Lotus corniculatus, Festuca arundinacea and Trifolium repens. Animals were managed under a forage allowance equivalent to 8% of body weight and supplemented at 1% of body weight. Productive variables evaluated included average daily gain, dry matter intake, feed conversion efficiency, dry matter digestibility and forage utilization. Results indicated no significant differences between treatments for final body weight (p > 0.05), dry matter intake (3.4 kg DM/animal/day; p > 0.05), forage utilization (34.7 ± 2.3%; p > 0.05). However, a significant effect of week on digestibility was observed (p < 0.05), with values increasing progressively throughout the experimental period from 42.5% at the beginning to 72.5% at the end of the trial. However, differences were observed in the growth curve, with older calves showing greater average daily gain (0.645 vs 0.553 kg/animal/day; p < 0.01), resulting in better feed conversion efficiency (5.38 vs 6.12 kg DM/kg BW; p < 0.001) compared with younger calves. Overall, the results suggest that a greater age at weaning may improve the productive performance of early-weaned Hereford heifer calves.