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Christopher McMullen, Karin Orsel, Trevor W Alexander, Frank van der Meer, Graham Plastow, Edouard Timsit
Faculty of Veterinary Medicine, University of Calgary, Calgary, AB, Canada.
Lethbridge Research and Development Center, Agriculture and Agri-food Canada, Lethbridge, AB, Canada.
Vet Microbiol. 2019 Apr;231:56-62. doi: 10.1016/j.vetmic.2019.02.030. Epub 2019 Feb 22.
The role of the respiratory bacterial microbiota in the pathogenesis of bovine respiratory disease (BRD) is still not well defined, limiting our understanding of the disease. Specifically, there is no information on the nasopharyngeal bacterial microbiota of cattle raised without antimicrobials. The objective was to characterize and compare the nasopharyngeal bacterial microbiota in feedlot cattle raised without antimicrobials that were healthy or diagnosed with BRD. Newly-received feedlot cattle (arrival bodyweight ± SD = 218 ± 37 kg) with BRD (n = 82) and pen-matched controls (n = 82) were clinically examined and sampled by deep nasopharyngeal swab (DNS). DNA was extracted from each DNS and the 16S rRNA gene (V4) was sequenced. Alpha and beta diversity were compared between health groups and among 3 days-on-feed (DOF) groups (group A = 3-12 DOF; group B = 13-20 DOF; group C = 21-44 DOF). Observed species richness was lower (P = 0.031) in cattle with BRD compared to healthy ones. Both health status (P = 0.007) and DOF groups (P < 0.001) were sources of variation in microbiota composition. Differences between health groups were driven by multiple sequence variants, including Mycoplasma bovis, Histophilus somni, and several Moraxella spp. Notably, M. bovis was more frequently identified in cattle with BRD. M. bovis identification was also higher in cattle sampled at later DOF. The increased identification of M. bovis in cattle with BRD reaffirms a potentially significant role for this bacterium in respiratory health.
牛呼吸道疾病（BRD）发病机制中呼吸道细菌微生物群的作用仍未明确定义，这限制了我们对该疾病的理解。具体来说，关于不使用抗生素饲养的牛的鼻咽细菌微生物群，尚无相关信息。本研究的目的是对不使用抗生素饲养的、健康的或被诊断为 BRD 的育肥牛的鼻咽细菌微生物群进行特征描述和比较。新接收的育肥牛（入场体重 ± 标准差=218±37kg），其中患有 BRD（n=82）和同栏对照（n=82）接受了临床检查和深部鼻咽拭子（DNS）采样。从每个 DNS 中提取 DNA，然后对 16S rRNA 基因（V4）进行测序。比较了健康组之间以及 3 天采食量（DOF）组（组 A=3-12 DOF；组 B=13-20 DOF；组 C=21-44 DOF）之间的 alpha 和 beta 多样性。与健康牛相比，患有 BRD 的牛的观察物种丰富度更低（P=0.031）。健康状况（P=0.007）和 DOF 组（P<0.001）都是微生物群落组成变化的来源。健康组之间的差异是由多种序列变异驱动的，包括牛支原体、溶血性巴氏杆菌和几种莫拉氏菌属。值得注意的是，M. bovis 在患有 BRD 的牛中更为常见。在较晚 DOF 采样的牛中，M. bovis 的鉴定率也更高。M. bovis 在患有 BRD 的牛中鉴定率的增加再次证实了该细菌在呼吸道健康中可能具有重要作用。
