The words Prime, Choice and Select on American beef are grades from the U.S. Department of Agriculture. Its beef standards were “established in 1916 and fully adopted in 1926.” Graders from the department’s Agricultural Marketing Service judge each carcass submitted for grading. The quality grade rests on the animal’s maturity and on the degree of marbling.
The grader judges the marbling “in the ribeye after the separation between the 12th and 13th ribs.” A University of Nevada meat scientist explains that “higher marbling degrees indicate higher grades, which are usually associated to better eating experience.” Grading is “a voluntary service.” Processors and producers may request it, at an hourly rate.