With just a half acre you could keep one but, you would have to supplement feed year round. As pointed out the mini's are just as expensive as the regular breeds. For a family milk cows jerseys are nice. Smaller so they are not as intimadating and they give wonderful rich milk to make things with. They also don't give as much as a larger breed (holstein, milking shorthorn, ashyire, etc.) would so much more family friendly that way.