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Urea dilution method was validated as an estimator of body composition . In this study urea space method was determined in 29 male growing Holstein cattle, although total body composition of 10 of them were determined through slaughtering. Chemical composition was also measured by using 12th and 9-10-11th ribs from each carcass. Urea space measured 12 minutes following urea infusion in jugular vein. Urea space was also evaluated as a biological entity using the composition indicated by the regression equations relating urea space to body composition. The regression equations relating total body composition. To The regression equation relating total body composition to the ribs composition showed that , the ribs composition Showed that, the ribs composition may be used for estimation of carcass composition . In both approaches., the observed urea dilution results agreed with the predicted values. It was concluded that urea space measurement can be used as a practical estimator of carcass composition of live growing Holstein cattle