Bovine Coronavirus Prevalence and Risk Factors in Calves on Dairy Farms in Europe

Simple Summary This study evaluated the prevalence and risk factors in health, management, and biosecurity of bovine coronavirus (BCoV) in neonatal and weaned dairy calves on 125 dairy farms in 17 countries in Europe. All farms had BCoV antibodies in the bulk tank milk. BCoV was detected by RT-PCR in 80% of dairy herds, and 24% of neonatal calves, 23% of weaned calves, and 4% of fresh cows sampled were shedding BCoV in nasal and/or fecal samples. The biosecurity on 109 dairies scored with Biocheck was, on average, 60% (external score 71%, internal score 47%), indicating that many farms are poorly protected from the introduction of BCoV onto a farm and spread within a farm. Dry cow vaccination against BCoV reduced shedding in neonatal calves, whereas it was linked to increased shedding in weaned calves in these farms. Several calf husbandry factors, such as transition milk feeding, milk feeding levels, group housing, and weaning age, were associated with BCoV shedding in calves.Abstract This study evaluated prevalence and risk factors in health, management, and biosecurity of bovine coronavirus (BCoV) in neonatal and weaned dairy calves on 125 dairy farms in Europe. Nasal and fecal swabs from neonatal calves, weaned calves, and fresh cows were analyzed for BCoV using RT-PCR, and blood and bulk milk samples were collected for BCoV antibody levels using ELISA. Multiple logistic regression models with random effects of herds were used to evaluate the herd health status, husbandry, management, and biosecurity associated with BCoV shedding (nasal and/or fecal PCR positive samples) in neonatal and weaned calves. BCoV was detected in 80% of herds and in 24% of neonatal calves, 23% of weaned calves, and 5% of fresh cows. The biosecurity scored on 109 dairies with Biocheck.Ugent was, on average, 60% (external score 71%, internal score 47%), and there was no clear association between various biosecurity measures on BCoV shedding in calves. Dry cow vaccination against BCoV reduced shedding in neonatal calves, whereas it was linked to increased shedding in weaned calves in these farms. Several husbandry factors, including nutrition (transition milk feeding and milk feeding levels) and management (group housing and weaning age), were associated with BCoV shedding in calves.