The Effects of Weaning Strategy on the Physiology and Performance of Beef Calves

Two experiments examined growth performance and physiological measures of stress in pre- and postweaned Angus steers (313 ± 24.5 kg; n = 48/Exp.), where steers were fitted with (YD) or without (ND) an anti-suckling device (Exp. 1), or provided (YS) or not provided (NS) a grain supplement (Exp. 2) for 7 d and weaned by fenceline (FS) or total separation (TS). Steers in Exp. 1 were weighed and bled on d 0, 3, 7 10, 14, 21, and 42, and in Exp. 2, on d 0, 7, 10, 14, and 21 and provided a grain supplement on d 7-21. In Exp. 1, weight gain was not different (P = 0.74) between ND and YD steers during preweaning. The YD-FS steers lost weight (P = 0.01) by d 10 compared with YD-TS steers. Hematocrit (Hct) increased (P = 0.04) in YD but not ND steers on d 3. Neutrophil:lymphocyte ratio (N:L) increased (P < 0.01) in all steers by d 7. Cortisol values in YD-FS steers were higher (P < 0.05) compared with YD-TS steers on d 10 and 21. The ND-FS steers had higher (P = 0.04) interferon-gamma (IFN) concentrations on d 10 compared with all YD steers. Haptoglobin (HAP) values increased (P < 0.01) in all steers by d 3. The FS steers had higher (P < 0.01) ceruloplasmin (CER) values by d 10 than TS steers regardless of preweaning treatment. Ovalbumin-specific IgG increased (P < 0.01) in all steers 10 d following its administration. In Exp. 2, NS-TS steers lost weight (P < 0.01) between d 7 and 10 compared with the remaining steers. The YS steers had higher cortisol, N:L and CER on d 7 compared with NS steers. Moreover, NS steers had higher (P < 0.01) Hct on d 10 than YS steers. Based upon physiological and growth performance data, it may be concluded that use of an anti-suckling device prior to weaning does not improve the animals’ well-being and, providing a grain supplement beginning 7 d prior to weaning may temper the animals’ stress response due to weaning when total separation is employed.