PREDICTION OF LEAN YIELD OF BEEF CARCASSES

Abstract

Detailed carcass cut-out data were obtained over two years on 149 Shorthorn bulls slaughtered at approximately 14 months of age. Carcass yield was measured on a closely trimmed basis, bone-in and boneless, and finally on a boneless-defatted basis. Simple carcass measurements were used singly and in multiple regression to predict lean meat content. Significantly larger average loin eye area measurements and smaller average rib fat measurements were obtained at the 12th–13th rib face than at the 11th–12th rib face [Formula: see text]. Fat measurements taken at the 12th–13th rib were more highly related to lean yield at all levels of trim than were fat measurements taken at the 11th–12th rib. Two intrascope measurements of the subcutaneous fat taken on unribbed carcasses and used in multiple regression had predictive value equivalent to the sum of three rib fat measurements at the 12th–13th rib. Rib fat measurements plus loin eye area provided equations which predicted carcass yield with good precision. Inclusion of carcass weight in the equation improved precision slightly. Inclusion of kidney fat percent was of no value. Maximum precision was achieved by including the variable trimmed round percent. A number of simple and multiple regression equations are presented and comparisons made with prediction equations developed elsewhere. Implications regarding beef carcass grading and beef sire testing programs are discussed.