USDA Grades for meat
The United States Department of Agriculture (USDA) meticulously grades beef at the request of a meat packer. Only beef that is USDA inspected may carry the USDA shield of authenticity. The grading system determines the quality rating of beef based upon a very complicated inspection system which measures the amount of marbling (fat specs) in the ribeye muscle (lean) portion and combines the maturity (age) of the beef carcass to determine the inspected grade.
The higher the ratio of marbling and the younger the beef, the higher the grade. It is the fat marbling which determines tenderness, juiciness and flavor. The age of the beef determines beef texture and also effects flavor. Younger beef produces a finer texture and a lighter red color.
USDA Prime is the best and is produced from young, well-fed beef cattle. It has abundant marbling and is generally sold in restaurants and hotels. This grade has the highest rating of a combined high ratio of marbling with the youngest maturity of beef. That's why prime is the most flavorful and most tender with the finest of texture.
Choice grade is high quality but has less marbling than Prime. Choice roasts and steaks from the loin and rib will be very tender, juicy, and flavorful and are, like Prime, suited to dry-heat cooking. Many of the less tender cuts, such as those from the rump, round, and blade chuck, can also be cooked with dry heat if not overcooked. Such cuts will be most tender if "braised" — roasted, or simmered with a small amount of liquid in a tightly covered pan.