I have two full size Jersey heifers and two Jersey cows. One cow is pregnant and due in November. I haven't been able to catch when the two heifers and cow have been in heat for the past six months. Sometimes I'll see them mounting, but I check and see nothing. I've used markers and all that. This is one problem. I've been looking into miniature Jerseys, but they're too small for my liking. So I thought, what if I bought a mini Jersey bull and bred him to the full size jerseys. That might solve two problems, but create more problems. If I move the pregnant cow to a pasture close by, will the bull not be satisfied with the two heifers and cow he has in his field, and still attempt to tear my fences down to get to the pregnant cow? Or does the cow have to be in heat before a bull will tear fences down? I had a dexter bull a couple years ago and didn't have too many problems, but I didn't have the cows split up.