In this paper, we examine different approaches to explaining decision support in herd management systems for their effects on comprehensibility and trust. To this end, we present a hypothetical system for assessing the risk of mastitis, a common infectious disease in dairy cattle. For this system, we design four explanation formats to present risk assessments to farmers. We collect their feedback in a survey to get suggestions for designing systems that are well accepted. In our work, it was not possible to identify one explanation format that is preferable to all others. Rather, a finding was that herd management systems should optimally support multiple explanation formats and allow switching between them depending on the situation.