Epidemiological studies of enteropathogens of newborn calves in New Zealand dairy farms

iv General Preface v Acknowledgements vi List of Tables xi List of Figures xiii List of Abbreviations xiv List of Publications xv Chapter one: Introduction 1 Chapter two: Neonatal calf diarrhoea: a literature overview 4 2.1. The principles of rearing of newborn dairy calves, with particular reference to the situation in New Zealand 4 2.2. The economic impact of neonatal calf diarrhoea 8 2.3. Aetiology of neonatal calf diarrhoea: risk factors 8 2.3.1. Non-infectious risk factors for NCD 9 2.3.2. Infectious risk factors for NCD 10 2.3.2.1. Infections with Cryptosporidium parasites 11 2.3.2.1.1. Pathogenesis and Clinical signs of Cryptosporidium infection in calves 12 2.3.2.1.2. Epidemiology of Cryptosporidium infection in neonatal calves 13 2.3.2.1.3. Diagnosis and control of Cryptosporidium infection in neonatal calves 15 2.3.2.2. Infections with BRV and BCV in neonatal calves 18 2.3.2.2.1. Infections with BRV in neonatal calves 18 2.3.2.2.1.1. Pathogenesis and clinical signs of BRV infection in neonatal calves 19 2.3.2.2.1.2. Epidemiology of BRV infection in neonatal calves 19 2.3.2.2.2. Infection with BCV in neonatal calves 20 2.3.2.2.2.1. Pathogenesis and clinical signs of BCV infection in neonatal calves 21 2.3.2.2.2.2. Epidemiology of BCV infection in neonatal calves 22 2.3.2.2.3. Diagnosis of and control of BRV and BCV infection on farms 23 2.3.2.3. Infection with K99 24 2.3.2.3.1. Pathogenesis and Clinical signs of K99 infections in neonatal calves 26