This article deals with transformations in beef cattle breeding practices in North America from 1950 to 2000, and the implication of these changes across the Western world. It was a period of profound adjustment for beef cattle breeders, involving battles over genetic defects, the importation of new breeds, changing standards in relation to husbandry, and the extension of quantitative genetic breeding practices. These innovations would be echoed across Europe in the production of beef cattle and would also interact with the way dairy cattle were bred. This article explains the upheaval in beef breeding between 1950 and 2000, as well as how that upheaval affected dairy cattle breeding. Changes in beef breeding, in effect, modified the functioning of the entire cattle breeding world.