ABSTRACT

1. Turkey production has increased dramatically as genetic selection has succeeded in increasing body weight and muscle yield to fulfil increasing consumer demand. However, producing fast-growing, heavily muscled birds is linked to increased heat stress susceptibility and can result in pale, soft, exudative (PSE) meat. Previous studies indicated that pyruvate dehydrogenase kinase 4 (PDK4) is significantly reduced in PSE samples, suggesting this as a candidate gene associated with the development of this problem.

2. The objective of this study was to determine whether pre-market thermal challenge results in PSE meat as a result of differential expression of PDK4. Two genetic lines of turkeys were used in this study; the Randombred Control Line 2 (RBC2) and a commercial line. Turkeys were exposed to a pre-market thermal challenge of 12 h at 35°C followed by 12 h at 27°C for 5 d. Birds were slaughtered and processed according to industry standards. Pectoralis major samples were categorised as PSE or normal based on marinade uptake and cook loss indicators. In the first experiment, the relative expression of pyruvate dehydrogenase (PDH) and the phosphorylation state of PDH in normal and PSE turkey meat were analysed by western blotting. In the second experiment, the same samples were used to measure metabolite levels at 5 min post-mortem, comparing the normal to the PSE samples.

3. The results of the first experiment showed that PSE samples had significantly lower total PDH (P = 0.029) compared to normal meat. However, there was no significant difference in the degree of phosphorylation of sites 1, 2 or 3. In the second experiment, there were no significant differences in glycogen, lactate, glycolytic potential or ATP when comparing PSE to control samples.

4. These results suggested that a reduction in PDK4 expression alone does not explain the development of PSE meat.

摘要

1.由于遗传选择成功增加了体重和肌肉产量，以满足日益增长的消费者需求，土耳其的产量急剧增加。然而，生产快速增长，肌肉发达的禽类与热应激敏感性增加有关，并可能导致肉色苍白，柔软，渗出（PSE）。先前的研究表明，丙酮酸脱氢酶激酶4（PDK4）在PSE样品中显着减少，表明这是与此问题发展有关的候选基因。

2.这项研究的目的是确定PDK4差异表达是否会导致PSE肉类出现售前热挑战。在这项研究中，使用了两种火鸡遗传系。随机控制线2（RBC2）和商业线。土耳其在35°C的售前热挑战中暴露12小时，然后在27°C暴露12小时达5天。根据行业标准屠宰和加工鸟类。根据腌泡汁摄入量和蒸煮损失指标，将胸大肌的主要样本分类为PSE或正常。在第一个实验中，丙酮酸脱氢酶（PDH）的相对表达），并通过蛋白质印迹分析了正常和PSE火鸡肉中PDH的磷酸化状态。在第二个实验中，使用相同的样品在死后5分钟测量代谢产物水平，将正常样品与PSE样品进行比较。

3.第一个实验的结果表明，与普通肉类相比，PSE样品的总PDH显着降低（P = 0.029）。但是，位点1、2或3的磷酸化程度没有显着差异。在第二个实验中，当将PSE与对照样品进行比较时，糖原，乳酸，糖酵解潜能或ATP没有显着差异。

4.这些结果表明，单独降低PDK4的表达量不能解释PSE肉的发育。