Validation of an Automatic Scale Equipped with Solar Panels for Grazing Beef Cattle

Abstract Body weight (BW) is used to detect health and nutritional disorders in cattle, as well as calculate profitability of the production system based on weight gain curves. In grazing systems, measuring BW frequently implies moving animals, which is labor intense, stressful, and reduces grazing time and feed intake. All of which negatively impacts animal performance. An automated scale in the pasture can reduce labor and animal handling, while ensuring an accurate BW estimation. Our objective was to evaluate the functionality and accuracy of an automatic wireless scale system equipped with solar panels (SmartScale, C-LOCKTM), when compared to a conventional scale located at the cattle working facility. Eight multiparous beef cows were weighed in a 14-day interval for a period of 57 days with a conventional scale, while at the same time BW was measured daily with an automated scale located at the pasture in front of the water trough. This wireless system registers BW every time the animal approaches the water trough and automatically transmit it to a server via cellular network. Correlation between weighing systems was evaluated through a linear regression (R Core Team, 2019), where the adjusted R2 value was 0.99, determining an excellent linear relationship between values obtained by the conventional scale and values obtained by the automated scale. In addition, the automated scale registered the time of day, time spent in the scale, and number of daily visits. The probability to find an animal at the scale varies between 15% to 20% during daylight, decreasing under 9% during the night, with 2.56±1.50 average number of visits per day, where animals spend in average 2.94±1.84 minutes. In conclusion, the automated scale has the ability to measure BW with great precision and has potential to be used as a complimentary instrument to evaluate animal behavior in grazing systems.