Ultrasonic Scanning and Body Measurements for Predicting Composition and Muscle Distribution in Young Holstein × Friesian Bulls

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Abstract
Accuracy of ultrasonic and linear body measurements for estimating compositional characteristics of young Holstein × Friesian bulls (n = 260) in three weight categories (340, 470, 600 kg) was evaluated. In vivo measurements were Danscanner longissimus area and fat area at the first lumbar vertebra, wither height, body depth, hip width and heart girth. Compositional traits were carcass conformation; percentage of lean, fat and bone; and percentage of total dissected muscle in Group I (flank, brisket, foreshank), Group II (shoulder, forerib, neck) and Group III (rib, loin, round and hindshank) cuts in the right side of the carcass. Live weight just before slaughter was included as an independent, continuous variable in regression analyses so relationships could be examined on a weight-constant basis. Positive relationships (P<.05) were noted between wither height and percentage of bone; correlations and partial regressions in the analyses of lean percentage were negative. Relations between wither height and fat percentage were positive, but none was statistically significant. Wither height had a negative influence (P<.05) on percentage of Group I muscle in 470-kg and 600-kg bulls, but was positively correlated with Group III muscle percentages. Influence of other live body measurements was less pronounced. Multiple correlation coefficients for the seven right-hand members ranged from .31 to .64 in the three weight categories, indicating that 41% or less of variation in these variables was attributable to weight and the four linear body measurements. Significant correlations between ultrasonic measurements and some compositional traits were noted. Generally, however, there was relatively little difference in multiple correlation coefficients and standard errors of estimates with or without the inclusion of ultrasonic scanning measurements, along with other live measurements. Maximum R-values for percentage of fat, lean and Group III muscle, using all live measures, were in the .6 to .7 range. Copyright © 1986. American Society of Animal Science . Copyright 1986 by American Society of Animal Science.

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