Relative Value of Longissimus Dorsi Muscle Area at Eight Different Locations in Pork Carcass Evaluation

Carcass length, average backfat, percent ham and loin, and loin-eye area measurements at eight positions along the longissimus dorsi muscle were taken on 50 pork carcasses weighing from 135 to 150 lb. Cross-sectional area measurements of the longissimus dorsi muscle were made at the fifth, sixth, seventh, eighth, ninth, and tenth thoracic, and the first and sixth lumbar vertebra. Loin-eye area increased posteriorly from the fifth thoracic to the first lumbar vertebra, but remained constant from the first to the sixth lumbar vertebrae. With one exception the loin-eye areas at each of the eight positions were significantly related to each other. There was no evidence of any differences among the eight positions in the relationship of loin-eye area to percent ham and loin. Because of the high correlation of longissimus dorsi areas at different positions on the same carcass, there is little increase in accuracy of predicting percent ham and loin from measuring loin-eye area in more than one place. If cutting errors can be minimized, measurement of loin-eye area at the fifth thoracic vertebra may be advantageous.