I recently spent £7,500 on a young registered Black Angus bull, which I then put out with the herd, but he just ate grass all day and wouldn't even so much as look at a cow. In fact I was beginning to think I'd actually got a pretty poor deal and had paid more than he was worth, so I had the Vet come out to check him over. He said the bull was very healthy, but possibly still a little bit young. Anyway, he gave me some pills to administer once a day.
What an amazing difference! Within two days he'd started to service the cows -- all the cows. Then he broke down the fence and serviced all of my neighbour's cows. He's like a machine! I have absolutely no idea what was in those pills the Vet gave him, but they taste a bit like peppermint.