Ultrasonic Estimates of Fat Thickness and Longissimus DorsiArea in Lambs

Two hundred thirty-five live lambs were studied over a 3-year period to determine the usefulness of an ultrasonic procedure for measuring the l. dorsimuscle area and fat thickness. The l. dorsimuscle area in 81% of the lambs was ultrasonically predicted within 0.2 sq. in. of the actual area. A progressive increase in magnitude of correlations was noted during successive years. Ultrasonic and carcass fat thickness measurements taken at the 13th rib and 6-7th lumbar vertebrae were significantly (P<.01) correlated with carcass fat trim. Width and depth of the l. dorsimuscle were both highly correlated with l. dorsimuscle area. The l. dorsimuscle area was correlated with the weight of dissected muscles from the leg and loin. There was no significant difference between area of the l. dorsimuscle from lambs sired by rams of different phenotypic scores.These results indicate that fat thickness and l. dorsiarea of live lambs can be ultra-sonically measured with acceptable accuracy.