Adopting a grading scheme inspired by the Meat Standards Australia (MSA) system is considered an effective way to strengthen consumer confidence in beef across Europe. However, differences between Europe and Australia in cattle breeds, production systems, and consumer dietary habits require a re-examination of the links among carcass and muscle traits, as well as beef eating qualities. In France, cull cows constitute a major beef source, with Limousine cattle being one of the predominant breeds. Accordingly, this study evaluated 102 French Limousine cull cows to investigate the relationships among carcass, muscles, and beef eating quality traits, and to explore the predictive value of key biological indicators for beef palatability. A comprehensive dataset integrating carcass grading traits assessed using the EUROP grid and the MSA protocol, muscle physicochemical measurements, and consumer sensory scores of beef was analyzed using correlation analysis, principal component analysis (PCA), and linear mixed-effects modelling. In older Limousine cull cows, marbling showed minimal contribution to eating quality prediction. Instead, traits related to muscle development, including age, carcass conformation, and compression force, played a dominant role in determining eating quality (P < 0.05). Model performance differed between consumer-evaluated MSA grade groups, defined as high grade (MSA grade ≥ 3) and low grade (MSA grade < 3). High-MSA grade samples exhibited more comprehensive biological features and achieved higher predictive accuracy, whereas low-MSA grade samples showed reduced model performance, likely due to narrower sensory variation and higher trait homogenization. These findings indicate that predictors of beef eating quality depend on animal type and age. In older cull cows, predictors of eating quality are likely to be more specific, particularly those related to muscle structure and maturity, at least in part. Overall, these findings provide practical guidance for the beef industry in predicting beef eating quality and improving grading systems for cull cows.

In the Meat Standards Australia (MSA) and Guaranteed Global Grading (3G) grading schemes, beef marbling is scored visually in the chiller by accredited graders from 100 to 1190 marble score points in increments of 10. This study aimed to evaluate a hand-held camera (Q-FOM™ Beef) for determining MSA marbling scores of carcasses quartered between the 5th and 6th rib. The carcasses were scored by two accredited graders, including an expert grader (i.e. a more experienced grader). The R2 of correlation between scores of the two graders for 377 carcasses was 0.78 with a RMSE of 47.9. The R2 of correlation between the scores of the expert grader and the Q-FOM™ for 285 carcasses was 0.75 with a RMSE of 44.9. For the grader-to-grader comparison, 75.9 %, 97.1 % and 100 % of the values were within 50, 100 and 200 marbling points, respectively. For the comparison between Q-FOM™ predictions and the expert grader, 78.6 %, 96.8 % and 99.7 % of the values were within 50, 100 and 200 marbling points, respectively. Both between visual graders and the Q-FOM™ against expert grader showed acceptable accuracy performance and fulfilled the accreditation criteria defined by AUS-MEAT in Australia. Additionally, 124 Q-FOM™ images were assessed on-screen by the expert grader. The R2 of correlation between the in-chiller and on-screen MSA marbling scores was 0.78 with a RMSEP of 48.7. Thus, on-screen assessing met requirements for accreditation, and both in-chiller and on-screen visual assessments of MSA marbling score are acceptable inputs for developing a Q-FOM™ Beef marbling model.

Only few studies have used Near-Infrared (NIR) spectroscopy to assess meat quality traits directly in the chiller. The aim of this study was therefore to investigate the ability of a handheld NIR spectrometer to predict marbling scores on intact meat muscles in the chiller. A total of 829 animals from 2 slaughterhouses in France and Italy were involved. Marbling was assessed according to the 3G (Global Grading Guaranteed) protocol using 2 different scores. NIR measurements were collected by performing 5 scans at different points of the Longissimus thoracis. An average MSA marbling score of 330-340 was obtained in the two countries. The prediction models provided a R2 in external validation between 0.46 and 0.59 and a standard error of prediction between 83.1 and 105.5. Results did provide a moderate prediction of the marbling scores but can be useful in the European industry context to predict classes of MSA marbling.

Protein turnover (PT), the continual synthesis and degradation of body proteins not leading to protein gain, is an essential high energy-demanding process. We assumed that PT might explain the between-animal variations of residual feed intake (RFI). The objective was to measure PT in extreme RFI cattle fed two contrasted diets (grass or corn-based). We conducted a RFI test for 84 days with 100 Charolais bulls and we selected the 32 most extreme (8 per diet and RFI group) for PT measurements using 1) the urinary 3-methyl-histidine to creatinine ratio, as a biomarker of the fractional protein degradation rate (FDR) of skeletal-muscle and 2) the isotopic N turnover rate measured in urine and plasma, as a proxy, respectively, of the whole-body FDR and the fractional protein synthesis rates (FSR) of plasma proteins. The 3-methyl-histidine and creatinine were determined from 10 d total urine collection. Isotopic N turnover in urine and plasma was evaluated by modelling the 15N depletion rate over 112 d following an isotopic N dietary change. Higher plasma FSR and higher skeletal-muscle and whole-body FDR were observed with corn-vs-grass diets (≥11%; P ≤ 0.03), in line with higher metabolizable protein and net energy intakes (≥10%, P = 0.001). Differences between extreme RFI animals were noted with the corn diets only, where efficient animals presented significant lower plasma FSR (-10%; P = 0.04) and numerically lower skeletal-muscle and whole-body FDR (-13% and - 8.9%; P > 0.16 respectively) than non-efficient. Non-significant differences were probably due to an insufficient size of our experimental setup. Plasma FSR is related to the PS of hepatic exportation, hence the lower plasma FSR observed in efficient RFI animals fed corn diets may reflect a lower organs to carcass ratio. Altogether results suggests that efficient RFI bulls fed corn diets had a lower hepatic PT with no-significant changes of whole-body and skeletal muscle PT.

Food safety crises involving persistent organic pollutants [POPs, e.g. dioxins, polychlorinated biphenyls (PCBs), organochlorine pesticides] lead to systematic slaughter of livestock to prevent their entry into the food chain. Therefore, there is a need to develop strategies to depurate livestock moderately contaminated with POPs in order to reduce such economic and social damages. This study aimed to test a POPs depuration strategy based on undernutrition (37% of energy requirements) combined with mineral oil (10% in total dry matter intake) in nine non-lactating ewes contaminated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and PCBs 126 and 153. In order to better understand the underlying mechanisms of the depuration process, POPs kinetics and body lipids dynamics were followed concomitantly over 57-day of depuration in POPs storage (adipose tissue, AT), central distribution (blood) and excretion (faeces) compartments. Faecal POPs concentrations in underfed and mineral oil supplemented ewes increased by 2.0 to 2.6-fold, but not proportionally to lipids concentration which increased by 6-fold, compared to the control ewes. Nonetheless, after 57 days of depuration in undernutrition and mineral oil supplementation, AT POPs concentrations were 1.5 to 1.6-fold higher while serum concentrations remained unchanged compared to the control ewes. This was concomitant with a decrease by 2.7-fold of the AT estimated lipids weight along the depuration period. This reduction of the volume of the storage compartment combined with the increase of POPs faecal excretion in underfed and mineral oil supplemented ewes led to a reduction by 1.5-fold of the PCB 126 AT burden, while no changes were observed for TCDD and PCB 153 burdens (vs. no change for PCB 126 and increases for TCDD and PCB 153 AT burdens in control ewes). The original approach of this study combining the fine description at once of POPs kinetic and of body lipids dynamic improved our understanding of POPs fate in the ruminant.