Key Laboratory of Animal Disease and Human Health of Sichuan Province, College of Veterinary Medicine, Sichuan Agricultural University, 211 Huimin Road, Wenjiang District, Chengdu, Sichuan, 611130, China.
Department of Pharmacy and Pharmaceutical Sciences, Faculty of Science, National University of Singapore, Singapore, 119077, Singapore.
Microbiome. 2024 Nov 16;12(1):242. doi: 10.1186/s40168-024-01962-2.
Long-distance road transportation is a common practice in the beef industry, frequently resulting in bovine respiratory disease (BRD) and compromised growth performance. However, a comprehensive investigation integrating clinical performance, physiological conditions, and nasopharyngeal microflora remains lacking.
This study aimed to evaluate the respiratory health and immunometabolic status of 54 beef calves subjected to a 3000-km journey. The respiratory health of calves was monitored over 60 days post-arrival using a modified clinical scoring system. Nasopharyngeal microflora and venous blood samples were collected at 3 time points: before transportation (A), 30 days post-arrival (B), and 60 days post-arrival (C), for 16S rRNA microbiomics, whole-blood transcriptomics, serum metabolomics, and laboratory assays.
Within the first week post-arrival, the appetite and mental scores of calves dropped to zero, while other respiratory-related scores progressively declined over the 60 days. The α-diversity of nasopharyngeal microflora in calves was similar at time points A and B, both significantly higher than at time point C. The structure of these microbial communities varied significantly across different time points, with a notably higher relative abundance of BRD-related genera, such as Pasteurella and Mannheimia, detected at time point A compared to B and C. The composition and gene expression profiles of circulating blood cells at time point A were significantly different from those at B and C. Specifically, higher expression levels of oxidative- and inflammatory-related genes, cytokines, and enzymes were observed at time point A compared to B and C. Higher levels of catabolism-related metabolites and enzymes were detected at time point A, while higher levels of anabolism-related metabolites and enzymes were observed at time points B and C. Additionally, significant correlations were found among microorganisms, genes, and metabolites with differing abundances, expression levels, and concentrations across time points. Stronger correlations were observed between calves' performance and nasopharyngeal microflora and immunometabolic status at time point A compared to B or C.
Collectively, these results confirm that 3000 km of road transportation significantly alters the composition and gene expression profiles of circulating white blood cells in calves, affects their metabolic processes, disrupts the balance of the respiratory microbial community, and leads to pronounced respiratory symptoms that persist for at least 60 days. During this period, the influenced composition and gene expression of circulating blood cells, metabolic processes, and nasopharyngeal microbial community gradually return to equilibrium, and the respiratory symptoms gradually diminish. This observational research indicates that transportation induces BRD in calves by disrupting the homeostasis of their immune function, metabolic processes, and nasopharyngeal microbial community. However, these results and their underlying molecular mechanisms warrant further validation through well-designed in vivo and in vitro confirmatory experiments with larger sample size. Video Abstract.
长途公路运输是牛肉行业的常见做法，经常导致牛呼吸疾病（BRD）和生长性能受损。然而，综合临床性能、生理状况和鼻咽微生物群的全面调查仍然缺乏。
本研究旨在评估 54 头经过 3000 公里旅程的肉牛的呼吸健康和免疫代谢状况。使用改良的临床评分系统在到达后 60 天内监测牛的呼吸健康。在 3 个时间点采集鼻咽微生物群和静脉血样本：运输前（A）、到达后 30 天（B）和到达后 60 天（C），进行 16S rRNA 微生物组学、全血转录组学、血清代谢组学和实验室检测。
在到达后的第一周内，牛的食欲和精神评分降至零，而其他与呼吸相关的评分在 60 天内逐渐下降。牛在鼻咽微生物群中的 α-多样性在时间点 A 和 B 相似，均显著高于时间点 C。这些微生物群落的结构在不同时间点显著不同，在时间点 A 检测到与 BRD 相关的属（如巴氏杆菌和曼海姆菌）的相对丰度显著高于 B 和 C。在时间点 A，循环血细胞的组成和基因表达谱与 B 和 C 显著不同。具体而言，与 B 和 C 相比，在时间点 A 观察到更高水平的氧化和炎症相关基因、细胞因子和酶的表达。在时间点 A 检测到更多与分解代谢相关的代谢物和酶，而在时间点 B 和 C 则检测到更多与合成代谢相关的代谢物和酶。此外，在不同时间点具有不同丰度、表达水平和浓度的微生物、基因和代谢物之间存在显著相关性。与 B 或 C 相比，在时间点 A 观察到牛的表现与鼻咽微生物群和免疫代谢状态之间的相关性更强。
综上所述，3000 公里的公路运输显著改变了牛循环白细胞的组成和基因表达谱，影响了它们的代谢过程，破坏了呼吸微生物群落的平衡，并导致明显的呼吸症状，持续至少 60 天。在此期间，受影响的循环血细胞组成和基因表达、代谢过程和鼻咽微生物群落逐渐恢复平衡，呼吸症状逐渐减轻。这项观察性研究表明，运输通过破坏牛的免疫功能、代谢过程和鼻咽微生物群落的动态平衡来诱导 BRD。然而，这些结果及其潜在的分子机制需要通过更大样本量的精心设计的体内和体外验证实验进一步验证。视频摘要。
