Health status of calves with and without the use of a herd-specific vaccine against Mycoplasmopsis bovis

The aim of this study was to evaluate the effects of a herd-specific vaccine against Mycoplasmopsis bovis (M. bovis; the genus name is similar to Mycoplasma;) on the health status of calves in Swiss fattening farms. In the run-up to this study, some farmers reported that they had significantly less problems with calf diseases on their farm since the use of a herd-specific vaccine than before. In order to test this statement in detail, six fattening farms were selected. There, the vaccination was given twice, 4 weeks apart, starting the first week after arrival, usually at an age of 4 weeks. Retrospectively, the treatment journals for one year before the use of the vaccine until one year after the use of the vaccine were evaluated and the disease incidences were calculated. The data were collected between March 2019 and November 2022. The monthly incidence of respiratory diseases in the chi-square test dropped significantly dependent on vaccination against M. bovis (p=0,034), varied between farms (p=0,001) and was found to be lower in summer compared to winter (p=0,006). The monthly incidence of otitis revealed no significant difference with regard to the use of the vaccine (p>0,05). The incidence of omphalitis was significantly different between farms (p=0,048), decreased with vaccination (p=0,022) and tended to be lower in summer compared to winter (p=0,058). Diarrhea showed a statistical tendency to be dependent from the farm (p=0,06). The monthly incidence of the sum of all diseases (otitis, pneumonia, omphalitis and diarrhea) was significantly dependent on vaccination against M. bovis (p=0,021). The results indicate that M. bovis is more important for calf health than currently assumed. M. bovis should therefore be considered more in diagnostics in order to perform an adequate therapy. The herd-specific vaccination against M. bovis improved general calf health potentially also due to a non-pathogen-specific immune response.