The use of ultrasound scanning at different times of the finishing period in lean cattle

This study aimed to evaluate the predictive ability of ultrasound at different ages based on the 10-12th rib-cut composition. Ultrasound measurements at different times of the finishing period and 10-12th rib-cut composition were measured on 163 bulls of three European beef breeds (Charolais, n=55; Limousine, n=55; Retinta, n=53). Ultrasound measurements (area and intramuscular fat percentage of the longissimus thoracis muscle, 12th-rib fat thickness, rump fat thickness, and gluteus medius depth) were taken every 30±5 days until slaughter (approximately at 180, 150, 120, 90, 60, 30, and 1-7 days before slaughter). Correlation and determination coefficients between ultrasound measurements and rib-cut composition were low-medium. The regression equations, developed from the live ultrasound measurements explained 45%, 43%, 35%, 35%, 35% and 36% of the variation in total lean, longissimus thoracis muscle, fat (total, subcutaneous and intermuscular) and bone percentages obtained by dissection of 10-12th rib-cut, respectively, and 34% in intramuscular fat determined by ether extract analysis of 12th rib. The predictive precision of ultrasonic measurements increased as animals approached slaughter, reaching maximum values at the last scan. When data from two or more scans were included, the last scan could be advanced in at least 30 days under the conditions of this experiment.