Precision livestock farming and other agricultural applications are considered to have great potential to utilise the many benefits of IoT technology. It is however important to maintain low cost and energy consumption to make it feasible in a very competitive market, making opportunistic and D2D communication interesting options. The demo will show a prototype of a system for monitoring grazing cattle in large free-range areas. We will demonstrate the mobile devices collecting data about the animals and their encounters with each other as well as the cloud platform that allows the farmer to access the data for more efficient operation of the farm