Immunization of dairy heifers with E.coli J5 vaccine in order to prevent and control mastitis caused by E.coli was evaluated. Prevalence of postpartum intramammary infections by this agent; clinical mastitis occurrence and severity in the first 100 days of lactation, and its influence on somatic cell counts (SCC) and milk yield were analyzed. Heifers (n=131) were randomly assigned into three groups of vaccinated and unvaccinated animals. Immunizations occurred at 60 days prepartum, 30 days prepartum and in the first week after calving. Milk samples were collected for microbiological diagnosis and SCC evaluation, and data related to clinical mastitis occurrence; its severity and milk yield were recorded. No reduction in prevalence of postpartum intramammary infections caused by E.coli was observed in vaccinated heifers. Vaccinated heifers had less clinical mastitis than the unvaccinated group. Milk SCC did not differ between the experimental groups. Milk yield was higher in vaccinated animals. Immunization with the E.coli J5 vaccine was effective in reducing the occurrence of clinical mastitis and increase in milk yield in the first 100 days of lactation but did not affect SCC, prevalence of intramammary infections and severity of clinical mastitis after calving.
dairy cattle; vaccine; mastitis; E.coli J5; coliform
