Estimating Carcass Lean in the Live Animal

North Carolina State University Animal Science Fact Sheet ANS94-803S. Carcass leanness and lean gain per day have become major concerns of both commercial and seedstock swine producers. This has resulted, to a large degree, from the development of the optical fat-lean probe and its addition to the major hog slaughtering plants. The optical fat-lean probe measures the external fat depth and loin eye thickness. These measurements are made by inserting a probe into the hog carcass in the area of the tenth rib. The measurements are then used in an equation that produces an estimate of the amount of lean in the carcass. The amount of lean, plus premiums or discounts, becomes the basis for the price paid for the carcasses. Hence, there is great interest among producers on methods to measure backfat and loin dimension on the live hog, and on the correct procedures to make individual animal-to-animal comparisons.