Post-weaning performance of Nellore calves subject to different weaning methods

Context. Different methods of weaning have been validated to reduce the stress of calves. A novel approach has been described by ranchers whereby the zebu calves are kept in the same pasture with trainer's cows, however, no scientific evidence is available to date. Aims. This study investigated the effect of different weaning methods on the physiological responses, temperament, and post-weaning performance of calves. Methods. One hundred and eighty three Nellore calves were used, including 93 males (initial bodyweight: 219.8 +/- 3.25 kg (avg +/- s.e.), initial age: 244 +/- 14.3 days (avg +/- s.e.) and 90 females (219.7 +/- 3.25 kg, 246 +/- 14 days (avg +/- s.e.)). The calves were randomly assigned to three weaning methods: Abrupt - total separation of dam and calf; Fenceline - physical separation between dam and calf by wired fence; and Leadership - total separation between dam and calf and use of social facilitator cows. Heart rate, respiratory rate and blood samples for cortisol analysis were taken on Days 0, 1, 4, and 7 post-weaning. Temperament was assessed on Days 0, 7, and 82. Performance and body condition score (BCS) was measured at 0, 42, and 82 days post-weaning. Key results. No interaction (P > 0.05) between the weaning methods and sex of the calves was detected. Heart and respiratory rates were not influenced (P > 0.05) by weaning methods on Days 1 and 7 post-weaning. Furthermore, females showed higher heart rate at Day 7 post-weaning (P < 0.05). Weaning methods and sex of calves did not affect the cortisol levels (P > 0.05). Calves on Fenceline and Leadership weaning methods had higher final bodyweight and average daily gain (ADG) from weaning until 82 days post-weaning (P < 0.05) compared to the Abrupt weaning method, which had negative ADG (-26 g/day) on the first 42 days and the lowest bodyweight until 82 days post-weaning (P < 0.05). Conclusions. The presence of social facilitators at weaning, using dams in the Fenceline method or non-related cows in the Leadership method, ensures greater post-weaning performance. The Leadership method can be the most advantageous due to its easy handling. Implications. The weaning strategies contribute to good animal performance and shorten the post-weaning and finishing phases.