Meat grading in the United States is based on a number of systems--one for each type of animal--and it has both voluntary and involuntary aspects. Although all meat requires inspection for wholesomeness--that is, safety for human consumption--quality grading is voluntary and is carried out by the manufacturer.
Beef in the United States is graded for quality--tenderness, juiciness, and flavour --and for yield--how much usable lean meat is given by the carcase. The grading scale contains eight levels and based on marbling, colour, and the maturity of the meat. The highest grade is not "A," but "Prime." Next is "Choice," followed by "Select," "Standard," and "Commercial." The lowest grades--"Utility," "Cutter," and "Canner"--are generally used only for ground and processed products.
Poultry in the United States is graded based on a letter system ranging from "A" to "C," with the former being the highest grade and the latter being the lowest. "Grade A" poultry, according to the U.S. Department of Agriculture, is the only grade that tends to be sold by retailers. The lower grades--"B" and "C"--are typically used for processed products and tend to be cut up and ground.
Unlike other meat and poultry, pork in the United States does not carry a USDA quality grade. This is because pork tends to come from pigs bred and raised to provide a similar type and standard of meat. The USDA suggests that appearance is important when buying fresh pork, noting that the meat should be firm and greyish-pink. Ideally, the meat should also have some marbling.
Lamb in the United States is graded by the USDA on a five-point scale ranging from the highest, "Prime," to the lowest, "Cull." The middle grades are "Choice," "Good," and Utility." According to the USDA, only the top two grades are sold retail. The lower grades are not usually marked. The department suggests that only USDA-graded lamb should be purchased, because the age of the animal and the quality of the meat can vary significantly in non-graded meat.