Use of Ultrasonics and Visual Appraisal to Estimate Total Muscling in Beef Cattle

Abstract

A Branson Sonoray instrument was used on 60 Hereford steers to estimate the cross-sectional area of the l. dorsi muscle. A detailed study was conducted on 10 of these steers, utilizing the same technique to evaluate other portions of the body in relation to carcass merit. Ultrasonic estimates of the loin-eye area and fat thickness were highly correlated with the corresponding carcass measurements (r=0.87 and 0.90, respectively). Ultrasonic estimates of the lumbar loin-eye area were highly correlated (r=0.82) with the corresponding carcass measurements. A definite variation in depth of l. dorsi muscle was revealed from the lateral estimates made by the Sonoray. Ultrasonic estimates of the biceps femoris thickness and forearm thickness were positively but non-significantly correlated with actual carcass measurements. Results of this portion of the study indicate that ultrasonics offer much promise as an objective tool for animal evaluation. Data from the visual appraisal study show that one of the three livestock judges successfully grouped steers by ranking them into light, medium or heavy muscling categories using adjusted loin-eye area as a basis for muscling. The F-test showed no significant difference between graders due to the limited data.