Bovine Respiratory Disease is the most costly disease among cattle arriving at feedlots and results in decreased weight gain, lower quality meat and death. BRD is highly transmittable and a rapid and sensitive diagnostic method for BRD is not currently available. This project will validate a state-of-art biomedical breath analysis sensor to assess the respiratory health of cattle. Our goal is to improve management of cattle by providing an immediate, objective measurement of respiratory health. OBJECTIVES: This project will test the validity of measuring an exhaled biomarker in bovine breath as a method of assessing respiratory health. Phase I work has established the technical merit and feasibility of breath testing bovine. During Phase II, we will 1) increase instrument sensitivity and improve breath testing methods, 2) validate Phase I results in calves infected and treated for BRD, 3) establish that biomarker monitoring can improve management of cattle during the feeding period, and 4) demonstrate the clinical capability of our technology by implementing our testing procedure into a commercial feedlot setting. APPROACH: The Breathmeter, developed by scientists and engineers at Ekips Technologies, is a laser-based breath sensor designed to quantify biomarkers in breath. Ekips has developed a sensitive and rapid platform instrument for the analysis of exhaled breath biomarkers. Ekips has demonstrated the use of this instrument for the analysis exhaled nitric oxide (eNO) in children and adults, and has demonstrated the successful measurement of eNO in cattle as an indicator of respiratory inflammation associated with BRD. A unique advantage of our technology is the simultaneous measurement of carbon dioxide which enables a direct determination of eNO concentration regardless of exhalation flow rate, a critical advantage in animal breath testing. We will continue to adapt our technology for use in cattle by improving instrument performance and sensitivity, improving breath testing technique, and eliminating affects of ambient nitric oxide