Active immunisation of pregnant heifers and cows in order to stimulate the development of antibodies against bovine rotavirus, bovine coronavirus and E. coli expressing F5 (K99) adhesin and to increase the level of passive immunity of calves against neonatal diarrhoea caused by bovine rotavirus, bovine coronavirus and E. coli expressing F5 (K99) adhesin.
In calves fed with colostrum and milk from vaccinated cows for the first week of life, laboratory studies conducted with heterologous challenge strains (a G6 BRV strain, a BCV strain and a K99 E. coli strain) have demonstrated that these antibodies:
-prevent neonatal diarrhoea caused by bovine rotavirus and E. coli expressing F5 (K99) adhesin,
-reduce the incidence and severity of neonatal diarrhoea caused by bovine coronavirus,
-reduce faecal shedding of virus in calves infected with bovine rotavirus and bovine coronavirus.
Onset of immunity:
In calves fed with colostrum from vaccinated heifers or cows, passive immunity commences with colostrum feeding and is dependent on calves receiving sufficient colostrum after birth.
Duration of immunity:
Calves fed with colostrum and milk from vaccinated dams for the first week of life are protected against bovine rotavirus for 7 days and against bovine coronavirus for 14 days. The duration of immunity against infections caused by E. coli expressing F5 (K99) adhesin was not studied since such disease is usually observed in calves less than 3 days of age and susceptibility to enterotoxigenic E.coli is age dependent.
