Calves must be permanently marked with a tattoo before they are eligible to be registered with the American Hereford Association.
Tattoos are usually placed in the ear. The tattooing equipment can be found at your local livestock supply and feed store, or you can purchase them online.
For some of the smaller, younger Mini calves, the 3/8″ tattoo digits are too large for their ear, so you might consider purchasing a smaller set, either the 5/16″ or the #300 sizes for goats or small animals. Differing theories on tattooing calves indicate to rub ink in the ear before applying the tattoo, or after. So long as the ink is well rubbed into the small punctures, the tattoo should be legible throughout the animal’s life.