Impacts of Cryptosporidium parvum Incidence during the first days of life on health and performance of dairy calves

Cryptosporidium parvum is a common enteropathogen causing neonatal diarrhoea in dairy calves worldwide. This condition reduces growth rates and normal development, leading to economic losses for dairy farmers. This cohort study investigated the impact of calf and dam-related factors on C. parvum incidence and evaluated the effects of early-life infection on health and growth. One hundred and forty calves were monitored from birth to 60 days of age. A high incidence of C. parvum was observed at 13 days of age. Calves that experienced difficult calving and had serum total protein levels <5.5 g/dl had a fourfold higher risk of C. parvum infection compared to those without these conditions. Early-life infection (≤8 days) significantly increased the risk of experiencing diarrhoea by four times and having diarrhoea lasting more than three days by three times. Additionally, calves infected within the first 8 days of life were nearly eight times more likely to gain less than 500 g of BW per day. This study highlights that difficult calving and inadequate immunoglobulin absorption increase the likelihood of early-life C. parvum infection, impacting calf health and growth. The impact of infection acquired during the first days of life represents a significant negative risk to calf health and growth, underscoring the importance of implementing management strategies to enhance animal welfare and reduce environmental contamination with Cryptosporidium oocysts.