Could be either. I would say since my herd bull weighs over 2000 lb it is more likely they would be bred by my retained bull calf.

As far as "poor management", in my situation I don't have the ability/facilities to separate groups during the summer. The rotational grazing system works much better, bulls are calmer and easier to manage if I run them all together as one group when there is grass.

I run three groups (cows+heifers, steers, bulls) over the winter from after weaning to steer harvest and then two groups (cows+springcalves+heifers, bulls) until bull in date in June. That is manageable when feeding hay and steers are grazing corn.

The lute shot is often used on all females in AI. It is a one time thing on heifer calves and not a big deal.

Breeding for a very fertile, early maturing cow herd requires caution with heifer calves.

I'm sure you will find fault with that, Mr Clicker, but the system seems to work. I don't really know if the heifer calves are bred or not but I don't like surprises. Mr Jdswmo would accuse me of "crippling heifers" if I didn't.