Rotavirus and enterotoxigenic Escherichia coli infections of calves on a closed Finnish dairy farm

Rotavirus and enterotoxigenic Escherichia coli infections of calves were surveyed during 2 successive years on a closed Finnish dairy farm consisting of 90–105 milking cows. From a clinical standpoint, diarrhoea was of moderate to high severity during the first year, compared to the milder disease in the second year of the study. Diarrhoea or abnormal faeces were found only in calves less than 8 weeks old, with the peak occurring during the first 2 weeks of life.In the first year, rotavirus was detected throughout the calving season in diarrhoeic or abnormal faeces of calves aged 1 day to 7 weeks. In the second calving season, rotavirus was detected only during the 4 autumn months and in calves aged 11 days to 8 weeks. Rotavirus was detected in only 1 sample of normal faeces in both years. Electron microscopy revealed no enteropathogenic viruses other than rotaviruses. Enterotoxigenic K99 E. coli was found in about half of diarrhoeic or abnormal faeces in both years and throughout the calving seasons. K99 E. coli was also found in 5–10 % of normal faeces.In the second year of the study, 45 of 101 pregnant dams were vaccinated with 2 doses of E. coli antigen. The vaccination trial did not prevent or reduce altered faeces in calves whose dams had been vaccinated compared with calves whose dams had not been vaccinated in the same year. Comparing the 2 years, the earlier uptake of colostrum together with better cleaning and disinfection of the calf house, contributed to the later and rarer occurrence of rotavirus infection in the second year of the study. The earlier uptake of colostrum together with better cleaning and disinfection of the salf house, in the second year, could not prevent enterotoxigenic E. coli infections in calves but partly prevented and modified the disease.