A note on the accuracy of an ultrasonic technique for selecting cattle of different breeds for slaughter at equal fatness

Abstract

ABSTRACTIn the first phase of the Meat and Livestock Commission's beef breed evaluation programme, cattle were slaughtered at a fixed subcutaneous fat percentage in carcass. Slaughter point was determined from fat areas measured over the m. longissimus at the 10th and 13th ribs by the Scanogram ultrasonic machine.The accuracy of the slaughter procedure was examined using data for 1367 cattle from the first 3 years of the programme. Subcutaneous fat percentage predicted from the ultrasonic measurements was compared with the percentage estimated by visual assessment of carcass fat cover. The s.d. of the difference between the two was 1·65.Data for a subset of 313 cattle were used to examine the relationships between the ultrasonically measured fat areas and actual subcutaneous fat percentage obtained by dissection. The residual s.d. for the prediction of subcutaneous fat within breed and production system was 1-18.The level of accuracy achieved was considered to be satisfactory within the context of the beef breed evaluation programme.