Just started calving with a small group of heifers. Charolais and Angus heifers(born here), bred to a Gelbvieh bull (I've owned him since he was 7 months old, and he's been here 15 months). These are his first calves also. So far, I’ve had 2 calves, both born dead. They’re all in great shape, and have been fed breeder select minerals throughout their entire gestation/pre-breeding. Calves were fully developed and completely normal looking. Any thoughts?