@Ky hills you are soooo correct. I started breeding Simmental back in 1970 with Fullblood semen. I had a mix of commercial cows. Anything that was black, potentially had a black calf. Since black gene is dominant, we all had black half bloods, then 3/4's to PB. I have NEVER bred with or to a PB Angus. Other than the original motly commercial cows we started with, I have bred to Fullblood then Purebred Simmental. Have always had black (or back in the day - diluted black) cattle. I never bred to a black Simmental bull until I used an embryo bull I raised (my avatar).
CAB was a great boost for BEEF. It was perfect timing, with Japan paying premiums for black hided cattle and the CAB program, black cattle became super popular.
Cornell Univ used to have a feedlot program. All my black hided steers qualified for CAB. I repeat - ALL qualified. Angus don't all qualify. They all qualify live requirments, but have a hard time passing the carcass requirements. Partly why breeders are chasing carcass NUMBERS. They have always required the live animal to be BEEF type, no dairy cross.
And also, for the record, research has proven that a 1600# cow does NOT eat twice as much as an 800# cow.