This study investigated the effects of acute stress on breast meat quality, redox status and mitochondrial function in pectoralis major (PM) muscle of broilers. A total of 168 broiler chickens (42-day-old, Ross 308) were randomly divided into control (CON) and pre-slaughter transport (T) treatments. A broiler was an experimental unit. Each treatment consisted of 84 broilers, and they were put in 12 crates with 7 broilers each. Broilers in the T group were transported according to a designed protocol, and the CON broilers were kept in crates under normal living conditions before slaughtering. Based on the meat quality traits assessed at postmortem 24 h, all PM muscles of the transported broilers were further classified into normal (T-NOR) and pale, soft and exudative (PSE)-like (T-PSE) groups for the determination of redox status in PM muscle and isolated mitochondria, energy metabolites, mitochondrial electron transport chain complexes activities, as well as mitochondrial function-modulating genes expression. Compared with CON, the extent of lipid peroxidation as well as protein oxidation were significantly increased in both PM muscles and mitochondria in T-PSE (P < 0.05), whereas not in T-NOR. Higher activities of glutathione peroxidase, total superoxide dismutase and Cu-Zn superoxide dismutase were observed in PM muscle of T-NOR broilers as compared with CON (P < 0.05). Pre-slaughter transport increased the generation of reactive oxygen species, as well as enhanced antioxidant capacity in PM mitochondria of broilers (P < 0.05). Compared with CON, the ATP content, activities of complex I and III, as well as relative mitochondrial membrane potential and swelling were significantly decreased in T-PSE (P < 0.05), whereas no significant changes in either ATP content or complex I activity were observed in T-NOR. Pre-slaughter transport enhanced the mRNA expression of regulators involved in the glutathione system, thioredoxin 2 system and mitochondrial biosynthesis in PM muscle of broilers (P < 0.05). Moreover, we noticed a more evident enhancement effect in T-NOR than in T-PSE (P < 0.05). Overall, this work indicates that acute stress-induced redox imbalance and mitochondrial dysfunction have significant implications for the development of PSE-like meat.

中文翻译：

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急性应激通过诱导氧化还原失衡和线粒体功能障碍降低 Ross 308 肉鸡的胸肉品质

本研究调查了急性应激对肉鸡胸大肌 (PM) 的胸肉质量、氧化还原状态和线粒体功能的影响。将总共​​ 168 只肉鸡（42 日龄，Ross 308）随机分为对照（CON）和屠宰前运输（T）处理。肉鸡是一个实验单位。每个处理由 84 只肉鸡组成，它们被放在 12 个板条箱中，每个板条箱有 7 只肉鸡。T 组肉鸡按照设计方案运输，CON 肉鸡在屠宰前在正常生活条件下饲养在板条箱中。根据死后 24 小时评估的肉质性状，运输肉鸡的所有 PM 肌肉进一步分为正常（T-NOR）和苍白，软和渗出 (PSE) 样 (T-PSE) 组，用于确定 PM 肌肉和分离线粒体中的氧化还原状态、能量代谢物、线粒体电子传递链复合物活性以及线粒体功能调节基因表达。与 CON 相比，T-PSE 中 PM 肌肉和线粒体中脂质过氧化和蛋白质氧化的程度均显着增加 (P < 0.05)，而 T-NOR 中则没有。与 CON 相比，T-NOR 肉鸡 PM 肌肉中谷胱甘肽过氧化物酶、总超氧化物歧化酶和 Cu-Zn 超氧化物歧化酶的活性更高（P < 0.05）。屠宰前运输增加了活性氧的产生，并增强了肉鸡 PM 线粒体的抗氧化能力（P < 0.05）。ATP含量与CON相比，T-PSE 中复合物 I 和 III 的活性以及相对线粒体膜电位和肿胀显着降低 (P < 0.05)，而在 T-NOR 中未观察到 ATP 含量或复合物 I 活性的显着变化。屠宰前转运增强了肉鸡PM肌肉中参与谷胱甘肽系统、硫氧还蛋白2系统和线粒体生物合成的调节因子的mRNA表达（P < 0.05）。此外，我们注意到 T-NOR 的增强效果比 T-PSE 更明显 (P < 0.05)。总的来说，这项工作表明急性应激诱导的氧化还原失衡和线粒体功能障碍对类 PSE 肉的发育具有重要意义。以及相对线粒体膜电位和肿胀在 T-PSE 中显着降低 (P < 0.05)，而在 T-NOR 中未观察到 ATP 含量或复合物 I 活性的显着变化。屠宰前转运增强了肉鸡PM肌肉中参与谷胱甘肽系统、硫氧还蛋白2系统和线粒体生物合成的调节因子的mRNA表达（P < 0.05）。此外，我们注意到 T-NOR 的增强效果比 T-PSE 更明显 (P < 0.05)。总的来说，这项工作表明急性应激诱导的氧化还原失衡和线粒体功能障碍对类 PSE 肉的发育具有重要意义。以及相对线粒体膜电位和肿胀在 T-PSE 中显着降低 (P < 0.05)，而在 T-NOR 中未观察到 ATP 含量或复合物 I 活性的显着变化。屠宰前转运增强了肉鸡PM肌肉中参与谷胱甘肽系统、硫氧还蛋白2系统和线粒体生物合成的调节因子的mRNA表达（P < 0.05）。此外，我们注意到 T-NOR 的增强效果比 T-PSE 更明显 (P < 0.05)。总的来说，这项工作表明急性应激诱导的氧化还原失衡和线粒体功能障碍对类 PSE 肉的发育具有重要意义。屠宰前转运增强了肉鸡PM肌肉中参与谷胱甘肽系统、硫氧还蛋白2系统和线粒体生物合成的调节因子的mRNA表达（P < 0.05）。此外，我们注意到 T-NOR 的增强效果比 T-PSE 更明显 (P < 0.05)。总的来说，这项工作表明急性应激诱导的氧化还原失衡和线粒体功能障碍对类 PSE 肉的发育具有重要意义。屠宰前转运增强了肉鸡PM肌肉中参与谷胱甘肽系统、硫氧还蛋白2系统和线粒体生物合成的调节因子的mRNA表达（P < 0.05）。此外，我们注意到 T-NOR 的增强效果比 T-PSE 更明显 (P < 0.05)。总的来说，这项工作表明急性应激诱导的氧化还原失衡和线粒体功能障碍对类 PSE 肉的发育具有重要意义。