Connecterra's Intelligent Dairy Assistant (IDA) is a novel Internet of Things based on a management support system for dairy farms. IDA uses sensor technology, cloud computing and artificial intelligence to support dairy farmers with insights on oestrus and health management. IDA analyses cow behaviour (originating from a 3D accelerometer on a neck collar) and herd patterns, and learns from the farmer's feedback. Within the Horizon 2020 project Internet for Food and Farm (www.IoF2020.eu) a field trial was conducted. The goal was to demonstrate that the IDA approach to generate actionable insights works. Therefore, we tracked KPI's on farm economics, animal health and fertility on two commercial dairy farms. We report the results of our trial from January to December 2018. Both farms had a herd of 100 cows, from which 50 cows were equipped with IDA. The farm KPI's were measured separately for the groups with and without. In comparison to the without group, the with group had, on average, its expected calving interval 5.92 and 0.88 days lower on Farm 1 and 2, respectively. Likewise, treatments with antibiotics 1.15 and 2.60 days shorter and 305 day milk yield 434 kg higher (Farm 1) and 405 kg lower (Farm 2) in the with group. For milk production the results are inconclusive as the groups were not balanced on milk yield before the trial started. We experienced in this trial, by qualitative feedback of the farmers, that the IDA approach worked and more observations are needed for scientific proof.