A Novel vaccine demonstrating prevention of neonatal calf diarrhoea

Abstract

A new maternal vaccine has been developed against neonatal calf diarrhoea associated with bovine rotavirus (BRV), bovine coronavirus (BCV) and Enterotoxigenic E. coli F5 (K99) (ETEC). This paper describes the results of 5 efficacy studies in target animals, conducted to gain Marketing Authorisation. Four studies were laboratory oral challenges (ETEC at 12 hours, BRV at 7 days, BCV at 7 and 14 days of age) in calves fed colostrum and milk for 7 days, from dams either vaccinated with a minimum potency vaccine, or placebo-injected, 11-12 weeks prior to expected parturition. One study was a field safety and efficacy study where pregnant cattle on a total of 3 farms were either vaccinated with a standard potency vaccine, 12 to 3 weeks prior to expected parturition, or left untreated. All animals were monitored – as well as their offspring, which received colostrum and milk from their dams - from 2 hours of age until 2 weeks post calving. The results of the challenge tests demonstrated that the vaccine successfully induced a significant and sustained antibody increase in cows and heifers to each vaccine component. Specific antibodies in colostrum and milk from the vaccinated dams transferred to calves, completely prevented clinical signs of diarrhoea after challenge from ETEC, BRV and BCV at 7 days, and significantly reduced their faecal virus shedding, compared with calves fed colostrum from placebo dams.  In the field study, vaccinated animals showed a modest temperature increase (+0.69°C on average) for a limited period (1 day on average), compared with untreated cows. No adverse impact was observed on pregnancy outcomes. Calves born to vaccinated cows showed a significant increase of all specific antibodies, compared with calves from untreated controls. The novel, non-oil adjuvanted vaccine achieved very high levels of efficacy and safety in rigorous studies and provides vets and farmers with a new tool against neonatal calf diarrhoea.