The most common disease in Finnish cows is udder infection and it also causes extra losses of income to dairy farmers. It´s not unambiguous to prevent and treat udder infections. The better you succeed in prevention of the inflammations the easier it gets when you treat the inflammation because you have less problems to solve how to treat the sick cow. Antimicrobial drugs are a common way to treat infections but part of bacterial strains has developed resistance towards these antimicrobials. Medicines also cause contingency time to the animal’s milk and meat. A new surprising problem was that a part of these commonly used antibiotics ended up from the market temporarily in 2015.

Antimicrobial effects of honey against different bacterial strains have been examined intensively all over the world and the results have been encouraging. There are two earlier previous investigations that have been carried out on Finnish honey´s antimicrobial effects against different pathogenic bacteria.

The purpose of this thesis was to explore possible antimicrobial effects of three different Finnish monoflower honeys and one multiflower honey against two different udder infections causing bacteria that occur in Finland. The monofloral honeys used in the laboratory exams were willow herb, buckwheat and dandelion honeys and the multiflower honey was mainly obtained from raspberry. The used bacterial strains were Streptococcus uberis and Klebsiella pneumoniae. As a part of this thesis an inquiry was conducted among the dairy farmers in the area of Tyrnävä, Ylikiiminki, Muhos and Utajärvi. The aim of the inquiry was to clarify how well the producers know the commercial products intended for promoting cow´s udder health including honey, beeswax or propolis or several of these. The aim of the inquiry was also to arouse interest in dairy farmers toward this subject of thesis.

The subscriber of this thesis was Adjunct Professor, Research Director Carina Tikkanen-Kaukanen from the University of Helsinki, Ruralia Institute.

We drew a conclusion that the agar well diffusion method was not a suitable method to explore antimicrobial effects. The method was not sensitive enough to detect any antimicrobial activity of these four honeys against any of the studied bacteria. Based on the results of the present work we recommend that in honey antimicrobial studies microbroth dilution assay should be used instead of well diffusion method. Those milk producers that answered to the delivered inquiry mainly replied that they hadn´t used honey, beeswax or propolis products or mixtures of them intended for promoting cow´s udder health.