Estimating Loin Eye Area in Swine with a Single Ultrasonic Measurement

In Experiment 1, data from 129 Duroc and Hampshire boars, barrows and gilts were used to develop a more rapid and much less expensive method of estimating longissimus muscle area in the live pig. The method involved ultrasonic measurement of the muscle depth at a point 6.4 cm from the dorsal mid-line and perpendicular to the skin at that point. Each centimeter of muscle depth approximated 1 in.2 of muscle area. Measurements of muscle depth from tracings of the muscle in the carcass were highly correlated (r=0.91) with actual muscle area at the 10th rib. The correlations of muscle depth with ham and loin percent (r=0.57) and lean cuts percent (r=0.56) were comparable to those between loin eye area and these two cutout measures (r=0.59). The method was tested on 74 pigs in Experiment 2. Ultrasonic estimates of longissimus depth in the live pigs showed correlations with actual area in the carcass at the 10th rib (r=0.67) and at the last rib (r=0.74) which are comparable to those found by other researchers using more elaborate equipment and/or more expensive techniques.