A Technique for Measuring the Cross-Sectional Axes of the Longissimus Dorsi Muscle and Fat Depth in Lambs1,2

A technique for measuring depth and width of the longissimus dorsi muscle was studied on 86 lambs randomly chosen from two separate feeding trials. Depth of the longissimus dorsi was estimated by needle probe over the right transverse process of the second lumbar vertebra. Width of the muscle was estimated as the width of the transverse processes of the second lumbar vertebra. The product of width and depth estimates was recorded as estimated cross-sectional area of the longissimus dorsi muscle. Depth probe was significantly correlated at the 0.01 level with actual cross-sectional depth of the muscle for carcasses of lambs from trials 1 and 2, 0.43 and 0.63, respectively. The depth probe estimate was highly significantly correlated, 0.56 and 0.59, with the cross-sectional area of the muscle in both trials. Estimated width of the muscle was not a reliable indicator of actual cross-sectional width. Estimated cross-sectional area of the longissimus dorsi muscle was significantly correlated at the 0.01 level with actual area of the muscle, 0.55 and 0.69 in trials 1 and 2, respectively.