Automating dairy farm grazing records using GPS technology

Long-term grazing records can be used to assess paddock productivity (e.g., grazings per year), yet inconsistent record-keeping among New Zealand farmers hampers accurate analysis. Recently, GPS ear tags have emerged as an automated solution for identifying and recording paddocks grazed, providing data that could be used to underpin on-farm decisions and aid sector scale tracking of pasture productivity. Two GPS-enabled ear tags (GSatSolar and Ceres Trace) powered by solar energy and reporting direct-to-satellite were evaluated on two Waikato dairy farms for recording grazing events. Five cows were fitted with GSatSolar ear tags on each farm, and a further four were fitted with Ceres Trace ear tags on the second farm. Comparing the GPS location data with manual grazing records revealed varying levels of accuracy in identifying the grazed paddock. The grazing records inferred using the GSatSolar ear tags correctly matched the manual grazing records on 58% of occasions on the first farm and 85% on the second farm, with the difference being attributed to the number of working devices between farms. By comparison, the Ceres Trace ear tags identified the grazed paddock on 91% of occasions. These findings suggest that it is feasible to automate the recording of on-farm grazing events using GPS-enabled devices. However, a greater number of devices should be deployed, and/or the location reporting frequency must be increased to identify the grazed paddock accurately. The considerations when choosing devices for these purposes are also discussed, including reporting frequency and tag attachment methods.