Blood biomarkers, infrared thermography, and meat quality in Nellore bulls under tropical conditions

This study investigated the use of stress-related blood biomarkers (cortisol, creatine kinase - CK, and lactate dehydrogenase - LDH) and infrared thermography (IRT) to predict meat quality in Nellore cattle under tropical conditions. These biomarkers reflect metabolic and stress pathways that influence muscle glycogen depletion before slaughter, contributing to elevated pHu and increased dark, firm, and dry (DFD) incidence. A total of 389 bulls from seven batches on the same farm were assessed at slaughter. Carcasses were classified by ultimate pH (pHu) as normal (pHu < 5.8), atypical DFD (5.8 ≤ pHu < 6.0), or typical DFD (pHu ≥ 6.0). The incidence of typical and atypical DFD meat was 20.8%. The typical DFD group showed significantly higher levels of cortisol, LDH, and CK. IRT images revealed that animals in the typical DFD group exhibited a higher minimum eye temperature (P < 0.003). In comparison, the atypical DFD group showed a higher maximum eye temperature compared to the normal group. Regression models demonstrated a strong predictive relationship (R² > 0.8) between cortisol, glucose, lactate, and pHu. We conclude that integrating blood biomarker analysis (specifically cortisol, glucose, and lactate) and IRT offers a practical tool for the early identification of DFD carcasses, which could enhance quality management in the beef industry.