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

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Abstract
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.
Funding Information
  • Fundação Amazônia Paraense de Amparo à Pesquisa (006/2019)

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