Prediction of body composition of live cattle using two ultrasonic machines of differing complexity: a report of four separate trials

Abstract

SUMMARYResults are reported from four separate trials carried out to determine the precision of the Sonatest (simple A-mode ultrasonic machine) and the Scanogram (modified linear scanner) for predicting the body composition of live cattle. Cattle in the four trials differed in breed, sex and origin, and the data provided an opportunity to determine the consistency of results in different circumstances. A total of 210 cattle were involved.Fat thickness measurements (Sonatest and Scanogram) and fat and M. longissimus areas (Scanogram only) were taken at the 10th and 13th ribs and at the position of the 3rd lumbar vertebra. Their precision as predictors of carcass tissues percentages was examined when they were used in addition to live weight at evaluation.There was little consistency between trials in the positions and measurements which gave the most precise prediction. The lowest within-breed residual standard deviations of carcass lean percentage obtained with fat thickness measurements taken by Sonatest were in the range 2·5–2·7 and there was little advantage in using additional measurements in multiple regression.Fat areas taken by Scanogram were more precise predictors (within-breed residual standard deviations were close to 2·0). Precision was improved marginally to about 1·8 by using combinations of fat areas but M. longissimus areas were of little additional value.