The current legislation of the FSVO prohibits the blanket usage of antimicrobials for cows at the end of their lactation. A differentation has to be made between "healthy" and "diseased" animals, which is currently being done using SCC measurements and bacteriological testing. Whereas "diseased" animals are allowed an antimicrobial treatment, "healthy" animals do currently not get any treatment. Not treating cows with a low SCC results in a decrease in antimicrobial usage but it coincides with a slight increase in clinical mastitis post dry-off (Scherpenzeel et al., 2014). Some "healthy" cows are truly infected at the end of lactation or they get a new IMI during the dry period, resulting in a higher incidence of clinical mastitis. There is thus a need to optimize dry off interventions to "healthy" cows. Work package 1 will meta-analyse the current scientific literature resulting in a ranking of non-antimicrobial interventions to healthy cows. It allows the FSVO and private veterinarians to update their guidelines regarding non-antibiotic dry-off strategies to "healthy" cows according to the best scientific evidence available. This is assumed to ultimately improve animal health and welfare of the cows post dry-off in comparison with drying off cows with no intervention.
Although there is generally a good probability for IMI to cure during the dry period after being treated with antimicrobi-als (around 80%; Halasa et al., 2009), variation around that estimation exists. The identification of prognostic factors predicting this probability of cure will identify subgroups of cows that benefit most (and least) from an antimicrobial intervention. This allows FSVO and private veterinarians to update their guidelines concerning antibiotic dry cow treatment by making them cow-specific rather than being based on the generic SCC threshold that is currently being used in Switzerland. Such a targeted dry cow intervention is eventually assumed to result in a more prudent and effective antimicrobial usage because only a subgroup of cows will be selected for antimicrobial treatment.
This project will have two work packages. Work package 1 will evaluate non-antimicrobial interventions aiming to prevent new IMI in healthy cows. Work package 2 will optimize antimicrobial interventions aiming to cure existing IMI. The aim of the first work package is to rank the effectiveness of various non-antimicrobial dry off interventions to cows with low SCC using a network meta-analysis. The aim of the second work package will be to identify subgroups of infected cows that are likely to benefit from an antimicrobial dry cow treatment using an individual participant data (IPD) meta-analysis.
