Instructions
Slaughter or Feeder
Determine if the sheep is a slaughter or feeder. The USDA applies identical grading standards to slaughter and feeder sheep. If an animal is identified as "slaughter," it is graded and sold with the intent to immediately harvest. Slaughter animals typically weigh between 100 and 150 pounds, with the lighter sheep typically marketed for ethnic or religious markets. If it is a "feeder" animal, it is typically a lamb needing increased growth. Feeder lambs are usually harvested when they reach between 50 and 100 pounds.
Determine the sheep's class. The USDA identifies a sheep in one of three classes: ram, ewe or wether. A ram is an intact male sheep, a ewe is a female, and a wether is a castrated male. Though there is no noticeable difference in meat quality between classes, the USDA still uses class as a segregating identifier.
Determine the sheep's age. There are three age classifications: lamb, yearling and sheep. Lambs are, roughly, under 14 months old. Yearlings are between one and two years old, and sheep are over 24 months old. A sheep's incisors mark the definite transition between age groups. If a sheep lacks incisors, it is a lamb; if it possesses one pair of incisors, it is a yearling; and two pairs indicate a sheep. Typically, younger animals produce meat more tender than the older. An older yearling or adult sheep is often referred to as "mutton." Because sheep usually ovulate just once a year (in the fall), market prices vacillate, particularly in the lamb age group.
Determine the quality grade. The USDA designates quality grade standards, applied and segregated per age group (lamb, yearling and sheep). Lambs and yearlings are quality graded Prime, Choice, Good and Utility. Adult sheep are graded either Prime, Choice, Good or Cull. Quality grade can be difficult to establish without experience. To properly grade a sheep, touch your two thumbs together and place them on the spine, directly above the tail. Extend your palms and outstretch your fingers, keeping them flesh against each other and with slight pressure against the animal. Run your hands toward the sheep's neck, keeping stable but light pressure against the animal. By using this method, you can assess the sheep flesh's thickness and firmness, and the uniformity of the fat distribution. Novices will find quality grading initially complicated, but an experienced grader can identify a sheep's quality grade with one hand swipe. Compared to the lower grades, the most desirable animals, the Prime followed by the Choice grades, have a smaller percentage of fatty tissue. Prime grades are more prevalent in lamb classes. Very rarely do older yearlings or adult sheep score Prime.
Determine the yield grade. While quality grade determines the palatability of the animal, the yield grade determines the proportion of quality meat compared to the waste (bone and fat). This is known as "cutability." Yield grades are designated between 1 and 5. Yield grade 1 is the most desirable, providing about 51 percent cutability. The lowest yield, grade 5.9, yields just slightly over 45 percent cutability. To determine yield grade, you must measure the thickness of the fat 4 inches below the ribeye. The thinner the fat layer, the better the yield grade: grade 1 sheep possess about .15 inches of fat above the ribeye, compared to about .45 inches of fat found on a yield grade 4 animal.
How to Grade Sheep
The United States Department of Agriculture, or USDA, issues official criteria for grading sheep. By implementing a grading system, the USDA provides consumers predictable quality when selecting meat, and sheep producers the ability to respond to the market demands. Not all sheep producers are held to federal USDA standards; 27 states host inspection and grading programs. The USDA permits state meat-inspection services, provided they at least meet the federal regulation levels. Therefore, state- and federally-graded sheep ascribe to USDA-mandated grading standards. When deciding a sheep's grade, the USDA takes into account the animal's class, age, quality and yield.