PSV-A-4 Novel Method to Identify Cattle Predisposed to Severe Cases of Bovine Respiratory Disease

Abstract Respiratory disease in several species can range from subclinical infection to acute death. Bovine respiratory (BRD) remains the greatest economic challenge facing beef industry. Histones are core proteins chromosomal structure that, when released extracellularly, cytotoxic and could contribute exacerbated tissue necrosis during infection. Work our laboratory demonstrated cattle suffering severe cases of BRD had limited capacity protect against effects extracellular histones, however, protective mechanism(s) remain unknown. Literature suggests components complement system interact with but on activity histones is unclear. The objective current experiment was evaluate feedlot heifers subsequent outcomes. Serum samples were collected 118 heifer calves (BW 229 ± 2.4 kg) at arrival evaluated for histone toxicity employing an assay; using a 50% hemolytic screening assay. Animals retrospectively assigned groups consisting of: not requiring treatment antibiotics (NT; n = 80) or that died within 1 wk entering (DA; 9). DA animals less (P < 0.001) than NT toxicity. Complement reduced 0.05) compared animals. Using ratio both assays under stringent selection points, positive predictive value 75%, negative 94%. Results indicate predisposed have impaired presumably contributing Analyzing these functional pathways may provide novel tool BRD.