Steer calves get only the mother's number, steers get a different colour tag than the heifers do.
Bottom number on heifer's tag is determined by order of birth, followed by the year letter. First calf born is 1A. Top number is the cows number. Metal tag is applied to heifer calves and noted in the herd book, so if in the future she should lose her dangle tag it can be replaced properly.
The dangle tag we give calves at birth is the only tag they will ever get as long as they don't lose it. I don't understand why people change out heifer's tags once they are bred.... perhaps someone can enlighten me
It's nice a nice feature when picking replacements, because at a glance you know who the mother is, and the chronological order of birth. Later on you can easily see families of cows and see what needs weeded out or is worth keeping.
Just my thoughts.