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An ultrasonic technique was developed and used to produce cross-sectional outlines of the rib-eye and associated fat at the 13 th rib of cattle and hogs. The procedure varied with development of technique and instrumentation from individual recording and plotting of reflected signals from numerous probings to a mechanized scan with one resulting photographic display. Since the procedure and data varied for different groups the data were treated in eight groups containing a total of 327 cattle and one group of 42 hogs. Correlation coefficients for ultrasonic and carcass fat thickness measurements were lower in most cases than those reported by other workers since the 1.0 me. frequency was used to obtain greater penetration. Comparison of ultrasonic rib-eye areas with carcass rib-eye areas gave significant but low correlation coefficients. These relationships were higher for hogs than for cattle. Comparison of repeated ultrasonic measurements indicated a significant repeatability of the method. Limited data suggest that the positional variation of rib-eye area and fat thickness between the 12 th and 13 th ribs, changes of shape and size of the rib-eye due to slaughtering, hanging and variability in pressure of the transducer against the hide during probing, are probable factors accounting for low relationships between ultrasonic and carcass measurements. The results of these investigations warrant additional refinement of the described technique in order to increase resolution and simplify evaluation of the results.
Stouffer et al. (1961) studied this question.