Cortisol increases in plasma of Holstein heifer calves from handling and method of electrical dehorning.

Changes in cortisol in plasma were used to assess stress when calves were restrained and then dehorned. Thirteen Holstein heifer calves between 3 and 4 wk of age were used over 4 d; each calf served as its own control. On d 1, 2, and 4, blood was sampled initially while calves were in a pen, 5 min after being placed in a restraint chute, and then at 5, 15, 30, and 45 min and 1, 2, 3, 4, 8, and 12 h after simulated or actual dehorning. On d 1, dehorning was simulated. On d 2 and 4, one horn bud of each calf was cauterized, respectively; sequence of horns (right, left) and dehorning instruments (conventional electrical, Buddex) were alternated for all calves. Day or previous dehorning procedures had no effect on initial concentrations of cortisol in plasma. However, after calves were placed in a chute, cortisol in plasma increased with each entrance. Cortisol in plasma peaked at 5 min posthandling (d 1, 11.3 ng/ml) or 15 min postdehorning (electrical, 21.9 ng/ml; Buddex, 20.7 ng/ml). These data suggest that both dehorning procedures resulted in similar rates of synthesis and secretion of cortisol.