Use of image analysis of cross-sectional cuts to estimate the composition of the 10th–11th–12th rib-cut of European lean beef bulls

• The R2 for predicting the carcass composition were moderate to high (0.535-0.761)
• Measures were more accurate in the 12th-13th than in the 9th-10th rib cross-section
• Computer image analysis can predict rib composition with fair accuracy in lean cattle

Data from 180 bulls from Charolais, Limousine and Retinta breeds were used to evaluate image analysis of cross-sections as method of predicting the physical composition of the 10th–11th–12th rib-cut. The site along the longissimus thoracis muscle (between either the 9th and10th ribs or the 12th and 13th ribs), and the breed had significant influence on most of the variables analyzed. The correlation coefficients between the rib composition obtained by image analysis and by dissection were low to moderate (r = 0.18–0.59, P < 0.01–P < 0.001). The R2 values of the composition components of the 12th–13th rib cross-section to 10th–11th–12th rib-cut composition were higher than those recorded from the 9th–10th rib cross-section (R2 = 0.535 to 0.759 vs. 0.148 to 0.502). The accuracy of the predictions of lean, longissimus thoracis m. and bone percentages improved significantly with the addition of carcass weight. Results indicate that image analysis can predict rib composition in lean cattle with moderate accuracy and precision.