Effect of post-weaning management practices on physiological and immunological responses of weaned beef calves

摘要

The objectives were: i) to investigate the physiological and immunological responses of previously grazed, abruptly weaned beef calves that were then either housed (H) and offered a diet of grass silage ad libitum plus concentrate or returned to familiar pasture (P) (Phase I), and ii) to examine the effect of subsequent housing (35 days post-weaning) on these responses in P calves compared with the H calves, which were acclimated to housing (Phase II). Rectal temperature was recorded and jugular blood was collected on days 0 (weaning), 2, 7, 14, 21, 28 and 35 (Phase I) and on days 0 (housing of P), 2, 7, 14, and 21 (Phase II). There was a treatment x sampling time interaction (P0.05) for rectal temperature, fibrinogen concentration, total leukocyte and lymphocyte number, and phytohaemagglutinin-induced interferon-gamma production during Phase I, with H calves having higher (P0.05) rectal temperature and fibrinogen concentrations on day 7, lower total leukocyte and lymphocyte number on days 7 to 35 and days 2 to 28, respectively, and reduced interferon-gamma production on day 7 compared with P calves. Neutrophilia (P0.05) was present in P calves on days 2 and 7 post-weaning. In Phase II, total leukocyte and neutrophil numbers increased (P0.05), whereas lymphocyte number declined on day 2 relative to values on day 0 of Phase II. In conclusion, deferring housing at the time of weaning resulted in a less marked stress response in beef calves compared with the traditional combined practice of weaning and simultaneous housing, however these changes were minimal suggesting that the overall health and welfare of beef calves was not compromised by abrupt weaning and simultaneous housing.