416 GPS precision and data acquisition efficiency of solar-powered collars and tags for beef cattle monitoring.

Abstract The use of GPS devices for tracking livestock has evolved rapidly. When integrated with pasture management, GPS devices can enhance understanding of cattle behavior, providing insights into grazing patterns and use within and among pastures. This study evaluates the horizontal error and fix acquisition success (FAS) rates of two GPS devices used for beef cattle. We positioned five mOOvement GPS solar ear tags (GPS-Tags; v.0.2.2; Moovement, Australia) and six Rumi GPS solar collars (GPS-Collars; two Rumi-Bull v.3.2 and four Rumi-Cow v.3.2S types; Innogando S.L., Spain) at a stationary location. The devices were placed on an open field, mounted on a wooden pole 1.5 meters above the ground, 10 cm apart, and 12 meters from the LoRa antenna. GPS-Tags and GPS-Collars data were collected over 82 days and 13 days, respectively. GPS-Tags recorded data every hour (24 fixes/d), and GPS-Collars recorded data every 10 minutes (144 fixes/d). To define each device’s “fix-true” location, we took the average of all the GPS locations for each device from its stationary position. Data analysis was performed using R statistical software (v.4.3.3). We used functions from the sf package to calculate the horizontal error (i.e., Euclidean distance) of each GPS location from the “fix-true” location. Next, we calculated each device’s mean horizontal error (m) on its stationary position. The FAS was computed as the percentage of successful fixes relative to the total expected fixes. For GPS-Tags, the FAS was calculated for the 82 days, with a separate calculation for 39 days, considering only days when the LoRa antenna and Wi-Fi router were fully functional. No additional FAS calculation was needed for GPS-Collars, as there were no issues during the 13-day trial. Considering all the days of the trial, a total of 4,057, 2,889, and 5,968 GPS data points were obtained from the GPS-Tags, Rumi-Bull, and Rumi-Cow, respectively. For the 39 days from the GPS-Tags, 3,797 data points were obtained. GPS-Tags had a mean horizontal error of 23.58 meters (± 1.44 SE), while the Rumi-Bull and Rumi-Cow collars had mean errors of 2.30 meters (± 0.12 SE) and 2.13 meters (± 0.08 SE), respectively. The FAS for GPS-Tags during the 82 days was 41.23% (± 1.91 SE) and 73.59% (± 1.63 SE) for the 39 days. The FAS was 77.16% (± 4.30 SE) for Rumi-Bull and 79.70% (± 0.73 SE) for Rumi-Cow. The GPS-Collars provided higher precision (i.e., less horizontal error), making them better suited for fine spatial resolution monitoring. Ultimately, the use of solar-powered GPS tags and collars, combined with advanced data interpretation, offers a powerful tool for enhancing the productivity and profitability of pasture-based beef cattle systems. These technologies contribute to data-driven decision-making, ensuring long-term environmental sustainability in complex grazing systems.