Kawasaki Takeshi, Iwasaki Tomohito, Watanabe Takafumi, Yamada Michi, Maeda Naoyuki, Hasegawa Yasuhiro, Takahashi Naoki, Kobayashi Ryosuke
Research Office Concerning the Health of Humans and Birds, Abashiri, 099-3119, Japan.
Department of Food Science and Human Wellness, Rakuno Gakuen University, Ebetsu, 069-8501, Japan.
J Poult Sci. 2025 Apr 5;62:2025014. doi: 10.2141/jpsa.2025014. eCollection 2025.
In this study, we aimed to identify the mechanism responsible for tissue degeneration and fibrosis in pectoral and supracoracoideus muscles. Ten chickens fed ad libitum broiler feed (Bro) were compared to 10 chickens fed breeding feed (Adj), which has lower metabolizable energy. The median body weight of Bro and Adj birds at 48 days of age was 4.9 and 0.9 kg, respectively. In Bro birds, hind legs were farther apart and tended to abduct, whereas their standing posture was often tilted forward, making them unstable. The two Bro males were heavier than the average, markedly less stable when standing or walking, and often flapped their wings vigorously to maintain balance. Myofiber damage and fibrosis were observed at the myoaponeurotic junction of the pectoralis major and supracoracoideus muscles in Bro birds. Myofiber damage and fibrosis were detected also in areas distal to the myoaponeurotic junction in the two heavier males but were otherwise less evident. By contrast, in Adj birds, almost no degeneration or fibrosis of muscle tissue was observed at the myoaponeurotic junction. In addition, the supracoracoideus muscle of one of the Bro birds showed coagulative necrosis of muscle tissue, surrounded by prominent fibrous tissue. Numerous incompletely formed blood vessels with irregular shapes and prominent branching proliferated in the fibrous tissue. These findings suggest that injury at the myoaponeurotic junction and abnormal capillary proliferation may be closely related to the formation of lesions, along with prominent fibrosis in the pectoralis major and supracoracoideus muscles.
在本研究中，我们旨在确定胸肌和胸上肌组织变性和纤维化的机制。将10只自由采食肉鸡饲料（Bro）的鸡与10只采食代谢能较低的种鸡饲料（Adj）的鸡进行比较。48日龄时，Bro组和Adj组鸡的体重中位数分别为4.9千克和0.9千克。在Bro组鸡中，后腿间距更远且有外展倾向，而它们的站立姿势常常向前倾斜，导致站立不稳。两只Bro组的公鸡体重超过平均水平，站立或行走时明显更不稳定，且常剧烈扑动翅膀以保持平衡。在Bro组鸡的胸大肌和胸上肌的肌腱膜连接处观察到肌纤维损伤和纤维化。在两只体重较重的雄性鸡的肌腱膜连接处远端区域也检测到了肌纤维损伤和纤维化，但在其他方面不太明显。相比之下，在Adj组鸡中，在肌腱膜连接处几乎未观察到肌肉组织的变性或纤维化。此外，一只Bro组鸡的胸上肌显示出肌肉组织的凝固性坏死，周围有明显的纤维组织。在纤维组织中，大量形状不规则且分支明显的未完全形成的血管增生。这些发现表明，肌腱膜连接处的损伤和异常毛细血管增生可能与病变的形成密切相关，同时胸大肌和胸上肌中存在明显的纤维化。
