Yu Miao, Xu Mengjie, Wang Guangju, Feng Jinghai, Zhang Minhong
State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, China.
Adaptation Physiology Group, Wageningen University and Research, Wageningen, Netherlands.
Front Microbiol. 2025 Mar 25;16:1504264. doi: 10.3389/fmicb.2025.1504264. eCollection 2025.
Long photoperiods are often characterized by enhanced oxidative stress-induced damage to skeletal muscle, reduced melatonin (MT) levels and intestinal microbiota dysfunction in broilers. In this study, we aimed to investigate the association of breast muscle morphology with melatonin levels and the cecal microbiota of broilers under different photoperiods. A total of 216 healthy 5-day-old Arbor Acres (AA) male broilers were randomly assigned to 12 L:12D, 18 L:6D and 24 L:0D photoperiods for 4 weeks (L = hours of light, D = hours of darkness). The concentration of inflammatory factors and MT concentrations was measured using ELISA kits, whereas breast muscle morphology was examined through the hematoxylin (H) and eosin (E) staining, and microbiota composition was identified through 16 s rRNA analysis. Extended light exposure significantly improved the growth rate of broilers, but significantly decreased feed efficiency (FE). Furthermore, it upregulated the concentration of IL-1β, IL-6 and TNF- and induced an abnormal breast muscle morphology. Extended light exposure significantly decreased MT levels in the hypothalamus, cecum and breast muscle, while triggering the cecal microbiota composition disorder. Specifically, there was significant alteration to the dominant bacterial phylum, following exposure to long photoperiods, with the abundance of Firmicutes decreasing and the abundance of Bacteroidota increasing. Notably, the relative abundance of showed a positive correlation with MT levels and a negative correlation with inflammatory cytokines. In conclusion, the present findings indicated that extended light exposure reduced the MT levels, which were related to disturbed cecal microbiota, damaging breast muscle morphology and inducing breast muscle inflammation in broilers.
长光照周期通常表现为肉仔鸡氧化应激诱导的骨骼肌损伤加剧、褪黑素（MT）水平降低和肠道微生物群功能障碍。在本研究中，我们旨在探讨不同光照周期下肉仔鸡胸肌形态与褪黑素水平及盲肠微生物群的关联。将216只5日龄健康的艾维茵（AA）雄性肉仔鸡随机分为12小时光照：12小时黑暗、18小时光照：6小时黑暗和24小时光照：0小时黑暗的光照周期，持续4周（L = 光照小时数，D = 黑暗小时数）。使用ELISA试剂盒测定炎症因子浓度和MT浓度，通过苏木精（H）和伊红（E）染色检查胸肌形态，并通过16s rRNA分析鉴定微生物群组成。延长光照时间显著提高了肉仔鸡的生长速度，但显著降低了饲料效率（FE）。此外，它上调了IL-1β、IL-6和TNF-的浓度，并导致胸肌形态异常。延长光照时间显著降低了下丘脑、盲肠和胸肌中的MT水平，同时引发了盲肠微生物群组成紊乱。具体而言，暴露于长光照周期后，优势细菌门发生了显著变化，厚壁菌门的丰度降低，拟杆菌门的丰度增加。值得注意的是， 的相对丰度与MT水平呈正相关，与炎症细胞因子呈负相关。总之，本研究结果表明，延长光照时间降低了MT水平，这与盲肠微生物群紊乱、损害胸肌形态和诱导肉仔鸡胸肌炎症有关。
