Yes, it can be a challenge to work with older calves. The other day I was feeding some yearlings, and one of them was never touched by a human hand in his life. I was feeding them some treats and walking around. They were following me quite nicely, so I showed the one who had never been touched, a halter. He sniffed at it and decided that it wasn't going to bite him. Then I slowly and carefully put it on him. He fought it a little bit, but didn't really take off. Then I started to lead him around. It was quite fun to see a cow who had never been touched until that day, then be haltered and led around.
I usually start them as soon as I can though. Generally that's at about a day old, maybe a little older. I'm training one right now, and she didn't really know that she should fight it. Now she's just at that age when she thinks that she can go where she wants to. I always win though.
