The results of this study showed that farmers in Module2, i.e. farmers that are allowed to initiate treatment themselves without prior examination of the cow by a veterinarian, had significantly higher behavioural intention to start medical treatment as the intention of ModuleVet farmers to contact a veterinarian. The case scenarios that measured behavioural intention were written in such a way that it was not obvious, under Danish conditions, if the case of MCM should be treated with prescription drugs the same day or not. Whether it is good to have a high or a low intention can be discussed. Not all MCM cases require medical treatment according to the behaviour intention found in this study; for example ModuleVet farmers would treat 50% of the MCM cases. ModuleVet farmers had a median intention score of 0.50, and this would have been 1.00 if the belief was that all the MCM behavioural intention scenarios presented should be treated medically on the same day as they were discovered.
The type of herd health programme and the attitude of the farmer described most of the variation in intention between the ModuleVet and Module2 farmers. The Module2 farmers had an odds ratio of 2.1 compared to ModuleVet farmers, which indicates that the Module2 farmers would be more likely to initiate treatment of a case of MCM on the same day as noticing it, whereas ModuleVet farmers might be more inclined to wait for a day or two before contacting the veterinarian for a visit, or may choose not to call the veterinarian at all. In a recent study, it was found that Denmark had the highest farmer detected treatment of clinical mastitis when compared with the other Nordic countries . These results are in line with the farmers’ relatively high intention score, 0.63 for Module2 and 0.50 for ModuleVet, to initiate treatment/call a veterinarian on the same day as they noticed a cow with MCM, when compared with findings in other Nordic countries. Compared to results from the TPB study carried out in the Nordic countries, Norwegian farmers had a behavioural intention score of 0.5, comparable to DK ModuleVet farmers, in contrast to 0.38 and 0.0 for Swedish and Finnish farmers, respectively [5, 6]. Finland has no intention to contact the veterinarian. However, in Finland it is more common to take a milk sample before contacting a veterinarian for a visit, and this explains the low intention found .
The differences in behavioural intention observed between farmers with the different herd health programmes in this study could be explained by variations in the cost of treatment. ModuleVet is associated with the more direct cost of a veterinarian’s fee, incurred when the veterinarian is contacted for a visit to a cow with MCM. Module2 farmers have medicine available at the farm, which means that the cost is more indirect because they have already paid for the scheduled visits by the veterinarian. It would be interesting to study the reasons why farmers choose the Module2 programme, for example if they already before entering had a more positive attitude to treatment of MCM than farmers who retain their Module1 or Core herd health programme. Or a speculation is that a higher behavioural intention to initiate treatment is a consequence of the easier access to, for example, antibiotics, that Module2 farmers have available on farm. Farmers with high attitude had 7.6 times higher odds of having high behavioural intention compared with farmers with a low attitude; this means that these farmers have a positive attitude towards medical treatment.
The median herd size for Module2 was larger than that for ModuleVet. This was expected, since the economic incentives to participate in Module2 are higher for large herds. On the other hand, there was no clear tendency for behavioural intention to differ among herds of different sizes with the same type of herd health programme.
Most farmers who participate in ModuleVet state that they never or only sometimes take milk samples without contacting a veterinarian. This is logical, because they would need to arrange a veterinary visit to have the cow treated with prescription drugs. However, there was a tendency for farmers who often take milk samples without first contacting a veterinarian also to state a lower behavioural intention to contact a veterinarian on the same day as detecting a case of MCM. This could be explained by, that these farmers have a strategy in which they await the results from a milk sample before a veterinarian is contacted. Interestingly, Module2 farmers stated the same behavioural intention to initiate treatment on the same day regardless of how often they take milk samples without first contacting a veterinarian. Farmers in Module2 are required to take milk samples if the cow is treated with any antibiotics other than penicillin. Whether farmers in Module2 initiate treatment of cases of MCM with such antibiotics depends on their herd health programme. This might be one explanation for the variation among Module2 farmers in their tendency to take milk samples without contacting a veterinarian first.
It could be expected that participating farmers did not initially have the same understanding of a MCM case. To overcome this issue great emphasis was placed on explaining the definition, both during elicitation interviews, in the questionnaire and ensuring that case scenarios in the questionnaire conformed to the IDF definition . In a study by Andersen et al.  it was shown that veterinary specialists did not agree on a mastitis definition based on concrete examples. However small differences in understanding of this definition would not be expected to make the results of this study invalid as the emphasis was on assessing differing treatment thresholds. If there was a different understanding of MCM this was likely random within the two groups. There is no evidence that Module2 farmers all thought of moderate/severe mastitis when answering questions about attitude, subjective norm and perceived behavioural control, and that ModuleVet farmers all thought of mild cases of clinical mastitis.
The questionnaire for the Module2 farmers was developed from the final ModuleVet questionnaire, which was developed to address differences in behavioural intention in the Nordic countries. According to Francis et al.  it is preferred that 75% of the most important statements obtained judged by the frequency that these statements are mentioned, from the elicitation study are represented in the final questionnaire. We included around 50% of the most important statements to avoid an excessively long questionnaire, which is one problem with the TPB approach. TPB-based questionnaires tend to be fairly complex; the questions asked need to be worded very precisely and can often be seen as repetitious . A long and complex questionnaire often results in a low response rate. Other authors have regarded a response rate of 20–30% as satisfactory , the response rates of 60% and 64% obtained in this study may be considered high. Still, selection bias, which may have affected the results, cannot be excluded. It is likely that there is an overrepresentation of farmers interested in treatment of mild clinical mastitis. Even if some farmers are more interested in mastitis, it may not mean that variation in behaviour either towards or against deciding upon treatment of mastitis is more uniform than in the rest of the population. The study herds were compared with the average of all Danish dairy herds and significance differences were obtained between Module2 study herds and all Danish dairy herds and even between ModuleVet and all Danish dairy herds. The study herds had in general higher production parameters. All farmers participating in the Module2 herd health programme were included in the study. It is not surprising that these herds differ from the average of all Danish dairy herds according to the production parameters since the choice of Module2 herd health programme may be influenced by both the herd size and the health status on farm. For ModuleVet there were no significant difference in the herd size and mean energy corrected milk yield per cow compared to the average of all Danish herds.