Impact of Two-Stage Weaning and Bovine-Appeasing Substance on Growth, Temperament, Pasture Behavior, and Immune System of Nellore Calves.

This experiment evaluated the effects of a nose flap (NF) device and bovine-appeasing substance (BAS) administration on the growth, temperament, immune response, and pasture behavior of calves during weaning. A total of 24 Nellore calves were used in a 2 × 2 factorial arrangement. The factors were the use of an NF or not (NoNF) for 14 d before weaning and the administration of BASs or not (NoBAS) at weaning (d 0). NF vs. NoNF reduced (p ≤ 0.01) the average daily gain (ADG; d -7 to 84; -0.289 vs. 0.378 ± 0.13 kg/d) and the time ruminating but increased (p ≤ 0.05) the exit score from the chute (d 14 and 28) and the time grazing. BAS vs. NoBAS administration increased (p ≤ 0.02) the ADG (d 14 to 84; 0.487 vs. -0.08 ± 0.10 kg/d) and the time grazing, reduced (p < 0.01) the time ruminating, and tended to decrease (p ≤ 0.10) the exit score (d 7, 14 and 28) and the time vocalizing. Treatments did not affect (p ≥ 0.35) serum rabies titer concentration. Thus, the use of NFs reduced growth and increased stress after weaning, while BAS administration increased growth and decreased stress after weaning, altering behavior but not the immune system. According to the results of this experiment, the use of BASs but not NFs is recommended to alleviate weaning stress in beef calves.