Associations of barn air quality parameters with ultrasonographic lung lesions, airway inflammation and infection in group-housed calves.

•Increasing temperatures are associated with ultrasonographic lung consolidation.•Odds of severe ultrasonographic lesions increase when air velocity is >0.8 m/s.•Prolonged exposure to >4 ppm ammonia is associated with mild lung lesions.•Cluster analysis using multiple parameters can aid in evaluation of barn climate.•Bacterial air load is not linked with respiratory disease in group-housed calves.