I have to agree with GoWyo. I assisted a neighbor the other day that has 16 cows. So far, he has had 2 AM, CA or fawn calves that had to be put down at birth (born alive) and 4 that have had fawn calf symptoms. Commercial cows with all angus pedigrees.
When I told him about the defects (which he had never heard of) he told the bull owner (a relative of his) to which replied "Get me the ears, as the bloodlines are tested clean". The rest of the story is yet to be discovered.
So please spare the "it is ok to sell carrier bulls to commercial cattlemen".