What kind of grass and how many acres are you using per animal unit? These are the things I look at. Is it profitable? It depends on largely on these things. In general, I think you are throwing money away when you fertilize and the cows are walking around in knee deep grass in every pasture. Either you need more animals or you need to back off on the fertilization. This is a tough balance to achieve and there are too many variables to give a good answer for your situation cause everybody's setup is different.