In the context of increasing antimicrobial resistance of microorganisms, there is growing interest in preventing the development and spread of antimicrobial resistance worldwide through the prudent use of antimicrobials and the reduction in antimicrobial use (AMU). Treatment of mastitis is the main cause for the application of antimicrobial substances in dairy cows. The aim of this study was to investigate associations between udder health, udder health management, and AMU. Factors AMU directly depends on should be found out to achieve the overall goal of optimizing antibiotic consumption without negative effects on
animal health. For this purpose, the subclinical and clinical udder health situation of 44 German dairy farms were analyzed at farm-level for the year 2020 using data from the Dairy Herd Improvement (DHI) testing and from herd-specific documentation on clinical cases. A questionnaire was used to describe the udder health management. AMU was measured by the mean number of days under antibiotic therapy due to mastitis per 100 cow years. The results showed that a higher clinical mastitis incidence (CMI) led to a higher AMU. The farm-specific mastitis treatment concept had an influence on the AMU as well. In addition, the actual existence of written treatment protocols was indicated to be
associated with higher antimicrobial consumption. However, as more details about the creation, quality as well as the frequency of use of the protocols were not recorded, this result should be interpreted with caution. In conclusion, our study confirms that CMI directly correlates with AMU on dairy farms. Therefore, reducing the number of clinical cases should remain in the focus of farms. Treatment protocols that consider the current state of science and the dynamics of mastitis pathogens on the farm can reduce AMU. They should always be developed with the supervising veterinarian and be regularly reviewed and
adjusted. It is also advisable to follow the latest scientific findings and, as far as possible, adapt the treatment concept accordingly, as modern treatment methods can also save on antibiotics.