Neighbor used to do exactly what youre talking about, bought some old dairy cow out of the sale barn, turned her in with the bulls and then put orphaned calves on her. I think he had 2 at the end, said you could have 4 calves on each one and they wouldn't go hungry as long as you kept good feed in front of the cow. 

I think he said the biggest trick was making sure she calved before the rest of the herd got going, otherwise youre back to bottle feeding until she calved. My luck shed be one of the last ones to calve. 

By watching CL I think the best thing might be throw the calf up on there and sell it for $400 and not have the risk, seems like theres always guys looking to replace calves.