I have several head of good quality registered Hereford cattle. One of my heifers was supposed to be bred but was not and one cow had a calf and the neighbors Brahma bull jumped the fence and may have bred them. How early in the pregnancy can a vet pregnancy check them and tell if they are bred? And if they are bred is there something I can do to make them abort the calf? I do not want to waste a calf by them having a bad one!