Assessed the effects of the cattle category or the rearing management on the 6th rib composition using image analysis

The relative proportion of muscle and adipose tissue in a carcass is an indicator of the yield and the quality of cattle carcasses and meat. The study's aim was to use image analyses to quantify the adiposity (subcutaneous, inter- and intramuscular fat) and longissimus muscle (LM) area, according to the cattle category or the rearing management. Data of 519 Charolais cattle (144 young bulls, 117 heifers, and 258 cull cows) were used. Five indicators were assessed from the image analyses: subcutaneous fat area adjoining the trapezius thoracis muscle (Trapez-Sub-Area), intermuscular fat area adjoining the trapezius thoracis muscle (Trapez-Inter-Area), LM area, intermuscular fat in the LM area enlarged by 25% (LM-Inter-Area), and LM's IMF (LM-Intra_Area). Image analysis confirmed that the adiposity of the females was significantly higher than the young bulls. However, the rearing management had few effects on the rib's adiposity whatever the cattle category. Young bulls that were slaughter older and receiving fattening diet with mainly hay, had a higher LM-Intra_Area than those that were slaughter younger and receiving corn silage in their fattening diet. The females that were fattened on pasture had lower Trapez-Inter-Area compared to those that were fattened in housing and fed a diet high in concentrates. For the cattle category and the rearing management of females, the results obtained through image analysis were similar to those obtained through grading methods.