Short communication: Ultrasonographic assessment of lung consolidation postweaning and survival to the first lactation in dairy heifers.

The aim of this prospective cohort study was to assess the association of systematic thoracic ultrasonography findings postweaning on calves' survivability to the first lactation. Three-month-old Jersey heifers (n=250) returning from a custom heifer grower were scanned by thoracic ultrasonography and lungs assessed using a scoring system with a scale from 1 to 4. A score of 1 was attributed to calves with no abnormality. A score of 2 was assigned if multiple comet tails or B-lines (coalescence of multiple comet tails) were observed. A score of 3 was assigned to calves with ≥1 location of lung consolidation ≥1 cm but <6 cm. Calves with extensive consolidation (≥6 cm in one or more locations) or evidence of abscessation or pleural effusion (>1 cm) were assigned a score of 4. Calves with a score of 4 had greater risk of dying or being culled [26% (95% credibility interval: 13-47%)] than calves with a score of 1 [1% (0-6%)], 2 [3% (1-9%)], or 3 [5% (1-17%)]. We found no association between age of first calving in the remaining calves and lung score. Thus, lung lesion severity assessed by thoracic ultrasound is associated with a long-term production outcome.