Investigations into the accuracy of prediction of beef carcass composition using subcutaneous fat thickness and carcass weight I. Identifying problems

Investigations were conducted into the accuracy of prediction of the percentages of fat and muscle in 69 steer carcasses using subcutaneous fat thickness and carcass weight. The carcasses were arbitrarily divided into low and high fat thickness, and light and heavy weight categories. Relationships between fat thickness and the percentages of fat and muscle were modified by breed and weight group (or their interactive effects), or by breed and fat group (or their interactive effects). General equations ignoring breed should not, therefore, be used for prediction. The equations were modified by using low and high fat thickness or light and heavy carcass weight groups. Because of the absence of breed differences in the lighter weight and lower fat thickness groups, a single breed-ignored regression equation could be used in each case to predict the carcass components. In the fatter and heavier groups of carcass significant breed differences occurred and breed specific regression equations should be used