The tracking of cows in large, extensive farms, as well as the possibility of checking on some veterinary data in real time, could open new business horizons for meat producers. A proposal for an electronic cowbell is presented, in order to provide an inexpensive technical solution for the exploitation of such free-running cattle. The idea is based on Zig Bee technology, which a rapidly developing technology. Different rural environments have been analyzed from propagation measurements, and an estimate of the number of network nodes (or “motes”) and the cost of the system is presented.