Arrival health indicators at a collection center and mortality risk in veal calves: a prospective cohort study (CLuBS study)

Veal calf mortality remains a major welfare and economic concern, especially during the early post-arrival period in the fattening units. In this prospective cohort study, we examined 934 calves upon arrival at a collection center using a standardized protocol (CLuBS), which includes easy-identify (C)linical signs, ultrasound-detected (Lu)ng lesions, (B)ody weight, and (S)erum total protein. Our goal was to evaluate how these factors associate with subsequent early (≤30 days) and total mortality during the approximately 180-day fattening period in veal calves. To analyze these associations, we used population-averaged logistic regression models with generalized estimating equations to account for clustering by farm of origin. Overall mortality was 11.6% (39/934 early; 108/934 total). In multivariable GEE models, severe lung consolidation (≥ 3 cm) emerged as the strongest predictor of mortality. Specifically, calves without lung lesions had significantly lower odds of early mortality (OR = 0.32; 95% CI: 0.11–0.94) and total mortality (OR = 0.34; 95% CI: 0.19–0.60). than calves with severe consolidation. Furthermore, arrival body weight was inversely associated with mortality, with a 13% reduction in early mortality odds (OR = 0.87; 95% CI: 0.82–0.93) and a 6.5% reduction in total mortality odds (OR = 0.94; 95% CI: 0.90–0.97) per additional kilogram. Additionally, higher rectal temperature was associated with lower odds of early mortality (OR = 0.50; 95% CI: 0.29–0.88; P = 0.015), whereas no association was observed with total mortality. These findings suggest that standardized arrival screening in a collection center, particularly lung ultrasonography and body weight assessment, provides clinically relevant prognostic information for mortality risk stratification in veal calves.