Antimicrobial use in dairy cattle explored through mixed methods. Focusing on the farmer-veterinarian collaboration

PhD student: Nanna Krogh Skjølstrup


Farmers and veterinarians are the primary responsible actors for refining or reducing antimicrobial use (AMU) within dairy cattle. Their collaborative framework of veterinary herd health consultancy (VHHC) comprises an obvious setting to explicitly work towards this task. Research shows that changing AMU is a complex issue for the individual farmer or veterinarian, involving many influential barriers and motivators. Identifying these factors and what in particular can influence veterinarians and farmers within a specific context remains an important task in achieving rational AMU. This thesis therefore aims to identify and clarify the factors that influence farmers’ and veterinarians’ AMU, both from a national and international perspective.

Once barriers to change and ways to overcome these have been identified, the next goal involves action to make real changes to AMU, and potential interventions to change AMU within dairy farming have previously been investigated. This thesis further investigates the potential for Stable Schools to instigate change in AMU without compromising animal health and production at Danish conventional dairy farms.

In order to ascertain whether the actions related to AMU (e.g. participation in a Stable School or other farm interventions), lead to an actual refinement or reduction in AMU, we need valid quantitative methods that can measure the development in AMU over time. This thesis therefore builds on previous experience of simultaneously measuring farm health, production and treatment records as a proxy for AMU, using state space models combined with collection of qualitative farm data.

Purpose of the Project

The overall aim of this PhD project was to investigate the potential to change attitudes and actions related to AMU in dairy cattle production within the context of Danish VHHC.

The overall aim was addressed through the following objectives:

  1. Review the internationally identified factors of relevance in terms of achieving rational AMU within the VHHC context in dairy cattle herds.
  2. Describe and analyse perceptions and practices related to AMU among Danish cattle farmers and veterinarians.

  3. Investigate changes in herd AMU, health and production during an advisory-based intervention from a longitudinal qualitative and quantitative perspective.

  4. Demonstrate the use of dynamic quantitative methods for monitoring and evaluating the effect of advisory-based interventions on herd AMU, health and production.


The results showed that a variety of factors influence the AMU of veterinarians and farmers. Therefore, veterinarians and farmers should take a person-specific approach in order to gain an understanding of what and how factors influence the individual’s AMU.

Legislation was found to have a particular influence on veterinarians and farmers, intertwined with perceptions of and attitudes towards AMR under Danish conditions. Furthermore, veterinarians seemed to base their treatment choices largely on personal experience due to a lack of locally valid and relevant scientific evidence about the effect of specific AMU choices. Both veterinarians and farmers were found to be influenced by their social environment, either through a pressure to prescribe or as inspiration for their own AMU choices.

None of the herds in the Stable School investigated in this thesis were found to have reduced AMU during the evaluation period. However, a change in attitudes towards AMU practices was observed. For the Stable School participants to achieve rational AMU, it was suggested that a specific common AMU-related goal should be set and the group should be facilitated in a way that allowed farmers with different learning modes and temperaments to benefit from participation.

It was demonstrated that state space models can be used for within-herd AMU evaluation. However, the specific application should be carefully considered and combined with qualitative data. It may be necessary to halt the evaluation and repeat it later if the conditions are not ideal, i.e. if there are many concurrent changes ongoing in the herd. 

Future perspectives

Future research should focus on the type of research results required to assist practising veterinarians with their everyday AMU choices. This research should optimally be applicable within a local farm context. As such, the AMU research could for example be an evidence-based template with guidelines on how the practising veterinarians could themselves create valid evidence relating to how to use antimicrobials in a specific farm context, i.e. what diagnostic tests to perform and a list of antimicrobials and treatment regimens that should be prioritised for specific diagnoses. The lists of preferred antimicrobials should be based on updated national results from surveillance of antimicrobial susceptibility testing.

In addition, the results of this thesis suggest a need to renew the Danish veterinary curriculum within VHHC or the apprenticeship in veterinary practice so that newly educated veterinarians feel better equipped to oppose the AMU preferences of farmers and colleagues and incorporate their most recently acquired knowledge about rational AMU in veterinary practice. Future research could focus on how the transition from student to practising veterinarian can be improved, for example by investigating the potential of a one-year post-graduate training programme conducted in collaboration between the university and veterinary practice. In such a programme, the newly educated veterinarian should engage in practice work but without the full responsibility of an educated veterinarian.