Up till very recently I would have said that I've heard stories about 8 month old bullcalves settling a cow or heifer, but never had one settle a cow before 11 months. But I just had a 20 month old commercial heifer calf completely out of season and the only possible sire is one of the bullcalves that was weaned at 8 months old. I always run weaned commercial replacement heifers with the registered cows after weaning and last year was the last spring calving season and the heifers was only with the last of the spring bullcalves for less than a week.
6-7 months. And he settled nine cows. I wouldn't have believed it other than there was no other bull on our farm and there are no other farms nearby. It was either him or the aliens I guess. We definitely didn't plan on it and were just keeping him in there til we sold him a few months later, didn't think he would be able to do anything.
I had a real nice Bull calf 11 months old that I wanted to breed to a pretty big heifer last year. This heifer was halter broke so we dug a hole to stand her in so he'd be tall enough to mount her. She settled in one breeding to him. These are angus. He could have probably bred one sooner. But he was on feed with bulls only after weaning. We always separate after or about 205 days.