PSVI-24 Evolution and risk factors of pulmonary lesions evaluated with thoracic ultrasonography in pre-weaned beef calves at arrival at the rearing facilities

Abstract

Abstract Bovine respiratory disease (BRD) is one of the main health problems in in pre-weaning calves at rearing farms. The aim of this study was to evaluate the evolution of pulmonary lesions using a thoracic ultrasonography and its association with predictable risk factors. Thoracic ultrasonography was performed in 811 calves (45–56 kg of BW and 3–4 wk of age) on 5 different rearing facilities at arrival and from d 12 to d 27 after arrival. Thoracic ultrasonography score was classified based on Adams and Buczinski (2016). Weight (light vs heavy), breed (dairy vs crossbred), source (national vs international), season, and number of calves arriving at the facility were recorded and used to evaluate risk factors. Data were analyzed using mixed effects models. At arrival 31% of the calvespresented pulmonary lesions, 21% were mild and 10% severe. After 12–27 d the number of calves without lesion decreased (P < 0.001; 70.3 ± 3.93% vs 34.0 ± 3.93%), number of severe lesions increased (P < 0.001; 8.9% ± 4.78% vs 40.1% ± 4.78%), however mild lesions were constant over time. Percentage of severe pulmonary lesions were greater (P < 0.001) when calves arrived in fall than spring, summer and winter; when calf source (P < 0.001) was international than national; and when their breeds (P < 0.001) were crossbred than dairy. A tendency (P = 0.09) was observed with the increase of severe pulmonary lesions with an increase of animals received by batch. At arrival, calves already had pulmonary lesions that increased in severity over time, therefore current health protocols do not mitigate BRD and more attention should be taken on risk factors such as breed, transport type and season.