"F1 Black Baldie" refers to the first generation offspring from a Hereford / Angus cross. Genetically speaking, F1's are highest in Hybrid Vigor.  Second, third and later generations have lost most of their hybrid vigor.  F1 Black Baldie cows are considered by ranchers, universities, MARC, and others to be the premier commercial American cow.  

Problem is, you'd have to tie up about a third of your breeding herd just to produce F1 replacements every year. 

Buying good replacements allows you to focus your production on a terminal cross to Angus, Continental, Composite bulls, or whatever, producing a larger number of uniform superior calves.

Looking at replacements going through an auction ring, it's hard to determine parentage. Black-hided, white-faced cattle might be from a Hereford bull bred to a black Saler, black Gelbveigh, black Simmental, later generation Hereford/Angus, or many other breeds. 

What we are offering is a source for good solid F1 Hereford/Angus replacement heifers. We raise our own for sale and we scour the west from Oklahoma to Montana, Video sales, auction houses, etc. looking for the right kind. This Fall, we will be offering long yearling   (18-24 month) heifers, ready to breed. 

Links:

Black Baldy Heifers Top Denver Commercial Sale
America’s Most Favored Cow
Heterosis and Its Impact