This study is based on an integromic approach of 71 young bulls' data from the farmgate-to-meat continuum including omics-based biomarkers, to understand beef tenderness variability in two muscle cuts that differ by their contractile and metabolic properties. By the means of chemometrics using partial least-squares (PLS) and principal component regressions (PCR), important variables from a list of 49 that characterize four levels of the continuum (rearing factors-carcass-muscle-meat) were identified to explain tenderness of Longissimus thoracis (LT) and Semitendinosus (ST) muscles evaluated by a sensory panel and instrumental Warner-Bratzler shear force (WBSF). The PLS and PCR analyses validated 16 and 15 variables for LT and 12 and 14 for ST from the whole continuum to explain sensory tenderness and WBSF, respectively. Among the explanatory variables in the four models and in line with the role of apoptosis in tenderness determinism, HSP70-1A/B (a heat shock protein) was retained to explain beef tenderness irrespective of muscle and evaluation method. Similarly, dressing percentage from the carcass level was another robust predictor but in a muscle-dependent direction manner. HSP20, ENO3, and MyHC-I as three muscle protein biomarkers and dry matter intake (DMI) as a rearing factor were involved in three models to explain beef tenderness. This study highlighted also that several variables were muscle-specific irrespective of the evaluation method of tenderness. For LT muscle, six variables including three carcass traits (fatness score, fat carcass %, and muscle carcass %), two muscle biomarkers (HSP70-8 and MyHC-IIx/b), and one meat quality trait (pH3h) were found. For ST muscle, five variables were validated from two rearing factors (average daily gain and feed efficiency) and three structural protein biomarkers (α-actin, MyBP-H, and CapZ-β). Finally, for WBSF only, lactate dehydrogenase chain B (LDH-B) was retained positively for LT and negatively for ST muscles. Overall, this trial showed that tenderness of LT and ST muscle cuts is influenced by variables belonging to the whole continuum with relationships that depend on both the muscle type and the evaluation method. It further highlighted the potential of integromic/chemometric approaches on the farmgate-to-meat continuum data to better understand the sophisticated biological processes that orchestrate the conversion of muscle into meat and tenderness determinism.
Keywords: biological mechanisms; biomarkers; bulls; chemometrics; integromics; meat tenderness.