Risk factors for neonatal calf diarrhoea and enteropathogen shedding in New Zealand dairy farms

•A cross sectional study of neonatal calf diarrhoea was performed on 97 New Zealand dairy farms.•Infectious and environmental risk factors for neonatal calf diarrhoea were identified using multivariable analysis.

To investigate the risk factors for neonatal calf diarrhoea, a cross-sectional study was conducted on 97 New Zealand dairy farms. Faecal specimens from 1283 calves were scored as liquid, semi-solid or solid, and analysed for bovine rotavirus (BRV) and coronavirus (BCV), enterotoxigenic K99+Escherichia coli (K99), Salmonella spp. and Cryptosporidium parvum. Calf- and farm-level data were collected by means of a questionnaire and the odds of liquid faeces calculated using mixed effects logistic regression models.Among the infectious agents, only C. parvum (odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.3-5.6; P = 0.02), BRV (OR = 2.7; 95% CI, 1.3-5.9; P = 0.01) and co-infection with more than one agent (compared with mono-infection: OR = 2.5; 95% CI, 1.3-4.8; P = 0.01) were associated with increased odds of liquid faeces in calves which were 9 to 21 days old. Housing of calves in open barns so exposing them to the weather was also associated with increased odds of liquid faeces compared with closed barns (OR = 2.1; 95% CI, 1.1-12.2; P = 0.03). Vaccinating cows against calf enteropathogens (OR = 0.2; 95% CI, 0.1-0.9; P = 0.03), administering waste milk (from mastitis and/or containing antibiotics; OR = 0.4; 95% CI, 0.1-0.8; P = 0.01), the sex of calves (females compared to males OR = 0.2, 95% CI, 0.07-0.7; P <0.01), and the use of straw for bedding (OR = 0.2; 95% CI, 0.03-0.9; P = 0.03) decreased the odds of liquid faeces. Conversely, in calves that were 1 to 5 days old, only K99 was associated with liquid faeces (OR = 4.6; 95% CI, 1.2-16.1; P = 0.02). In this age group, the odds of liquid faeces were smaller on farms where females took care of the calves, compared with males (OR = 0.4; 95% CI, 0.01-0.9; P = 0.04).