If you are going to dock your calves’ tails, you may want to avoid the period right before weaning. 

A University of Wisconsin study reveals differences in behavior among preweaned calves that are tail-docked, versus those that aren’t docked. Preweaned calves between 22 and 42 days of age demonstrated significantly more restlessness after application of tail bands than younger calves or those that weren’t docked at all. Restlessness, in this case, was measured by the number of times an animal stood up or laid down every 15 minutes.

In another experiment, which looked at the effect of tail docking on older animals, the researchers did not note any differences in behavior among heifers that were docked between 20 and 25 months of age. The docked heifers showed no signs of stress, as measured by plasma cortisol levels.

These findings were reported in the December 2002 Journal of Dairy Science.