Study adds evidence for more targeted BRD antibiotic use

A newly published gene expression study from researchers at Texas A&M, Mississippi State, and West Texas A&M adds evidence for a more selective approach to antibiotic use in high-risk stocker cattle. In the March 18, 2026, Scientific Reports paper, the team followed 84 commercial heifers randomized to receive tulathromycin metaphylaxis or no metaphylaxis at arrival, then tracked blood transcriptomic changes over 70 days. The study found that five immune-related genes were consistently altered in cattle at the onset of bovine respiratory disease, regardless of whether they had received metaphylaxis, while the researchers did not find clear transcriptomic differences at arrival that reliably predicted which animals would later get sick in this particular cohort. The work builds on the group’s earlier research showing that at-arrival blood gene expression can differ by later BRD outcome, and on broader industry efforts to replace subjective risk sorting with more objective tools. (nature.com)

Why it matters: For veterinary professionals, the practical takeaway isn’t that metaphylaxis is obsolete. It’s that the science around BRD risk stratification is getting more precise, and stewardship conversations are moving from blanket treatment toward identifying which cattle are most likely to benefit. That matters because BRD remains the leading reason for antimicrobial use in U.S. feedlots, metaphylaxis is still common in high-risk cattle, and unnecessary treatment in lower-risk cohorts carries both cost and stewardship implications. This study also highlights candidate biomarkers, including IL1R2, HP, S100A9, TLR4, and ALOX15, that could eventually support more targeted treatment or diagnostic tools. (pmc.ncbi.nlm.nih.gov)

What to watch: Watch for validation studies in larger, higher-morbidity cohorts, plus any movement toward practical blood-based or multi-omic BRD risk tests that could inform targeted metaphylaxis decisions on arrival. (nature.com)