125. Exploring the Relationship Between Nasal Passage Thermal Imaging and the Nasal Microbiome for Early Detection of Bovine Respiratory Disease.

Abstract Bovine respiratory disease (BRD) has persistently been the leading cause of morbidity and mortality of beef cattle in the United States. The nose is one of the first points of contact between the outside environment and inside the body, allowing pathogenesis through the airway and thus throughout the body, potentially leading to respiratory infections. The relationships between nasal temperatures, the nasal microbiome, and onset BRD has yet to be investigated, which may provide a further understanding of the BRD complex and could potentially serve as an early disease detection method. Crossbred beef calves (n = 479) that were considered high-risk were purchased from regional auction markets and used for various 42-d receiving studies. Cattle arrived on 5 separate dates and consisted of heifers (n = 202), steers (n = 134), and bulls (n = 143). On d 0, cattle underwent standard processing and were stratified by initial body weight and sex to be assigned to 1 of 8 or 9 pens (10 to 12 calves/pen). A subset of calves (4 to 5 calves/pen) were selected randomly for sampling procedures which included radiometric thermal imaging of the nose and nasal swabs. Subset samples were collected on d 0, 14, 28, and 42. If symptoms of BRD were presented and if rectal temperature was ≥ 40 °C, cattle were deemed morbid, treated with antibiotics, and underwent sampling procedures. Nasal swabs (n = 160) underwent 16S rRNA sequencing of the V4 region with an Illumina Miseq Sequencer. Correlation data were analyzed using Person’s product-moment correlations, Spearman correlations, and Chi-squared analyses of R programming (v5.5.0) and significance was declared if P ≤ 0.05. Microbiome data were analyzed with the QIIME2 pipeline. Amplicon sequence variants (ASVs) were considered differentially abundant using RandomForest and MaAsLin2. Time of year influenced the incidence of BRD (P < 0.01), which was greatest in January and the least in March. Nasal temperatures did not share a relationship with later BRD incidence during the 42-period (P ≥ 0.41). However, rectal temperatures were positively correlated with nasal temperatures (P = 0.01; r = 0.40) which were both recorded at the time of antibiotic administration. Differential abundance revealed ASVs associated with nasal temperature. Of these ASVs, ASV22_Histophilus (P = 0.01; r = 0.23), ASV24_Mesomycoplasma (P = 0.01; r = 0.23), and ASV361_Acetitomaculum (P < 0.01; r = 0.24) were each positively correlated with nasal temperatures. Meanwhile, ASV24_Methanoscorpulum (P = 0.05; r = -0.17) and ASV161_Staphylococcus (P < 0.01; r = -0.33) shared negative relationships with nasal temperatures. To conclude, exploring the relationships present in nasal passage environment and thermal imaging with BRD outbreaks could improve potential health risk assessment tools at receiving.