388 Epidemiological risk factor dynamics of Bovine Respiratory Disease in U.S. beef production systems.

Abstract Extensive research has explored the epidemiology and risk factors contributing to Bovine Respiratory Disease (BRD). However, its multifactorial etiology and complex onset have made attempts at managing its impact in beef production systems difficult to navigate. A comprehensive categorization of BRD risk factors and their variation across integrated beef production systems is crucial for improving prevention and management strategies. This paper analyzes the epidemiological patterns of BRD while categorizing and evaluating key risk factors that influence disease occurrence and severity in different production settings. BRD epidemiology including associated risk factors was assessed using a mixed methodology. A review of existing BRD epidemiology and risk factor literature was also conducted. Data on BRD risk factors was taken from 8 different databases and papers published between 2004-2024. One hundred and thirty-three (133) papers were screened following the PRISMA-ScR guidelines to generate a final list for inclusion in the review. Risk factors were classified into intrinsic (host-related or biological), extrinsic (environmental and management-related), and pathogen-associated categories. Key predictors of BRD, including transportation stress, commingling, nutritional status, age, and weather conditions were also identified and categorized based on how they vary across beef production systems. Our findings indicate significant variability in BRD prevalence and severity based on categorization of the risk factors. Transportation distance and commingling were strongly associated with increased BRD incidence in stocker and feedlot cattle, while low birth weight, inadequate nutrition and genetic challenges were dominant risk factors in cow-calf systems. For author-reported BRD morbidity and mortality, the risk profile, type of study and experimental population considered presented varying results over several years. The results of this study provide valuable insights into the epidemiological trends and risk dynamics of BRD within modern beef production. Our findings lay a foundation that will support the development of precision animal health strategies and data-driven decision-making for beef sustainability.