The California legislature recently passed a bill to ban the docking of dairy cattle tails. I was surprised when I read that over 80% of dairy farms in a study used tail docking, as I had worked on two dairies when I was young and was completely unaware that anyone did this.
A few months ago I spent time trying to find out why people were docking tails, and I could not identify any reason other than the nuisance of dealing with tails when milking. I could not find any health reason for doing so.