I also know several farmers ( friends for over 30 years) that buy Holstein bull calves, raise them for beef, and sell them to dealers that sell the beef as certified Angus beef.
They said the rules on what is certified Angus is so loose that any beef with black in the hide can get the label.
There are 10 criteria for meat being certified as Certified Angus Beef. All 10 criteria are inspected on the carcass. The inspectors don't ever see the cattle on hoof. A Polled Hereford can end up in your store as Certified Angus Beef.