Preliminary study on the application of robotic herding to manipulation of grazing distribution: Behavioral response of cattle to herding by an unmanned vehicle and its manipulation performance

Abstract

Robotic herding is attracting attention as a new technology for managing grazing animals. As a preliminary step toward the application of robotic herding to the manipulation of grazing distribution, we investigated the behavioral responses of cattle to herding by an unmanned vehicle and its performance in manipulating grazing distribution in a pasture. A herd of approximately 30 cows was stocked in a 1.1-ha pasture for 5 days each month from May to October 2021. The cows were herded by a small unmanned ground vehicle for 7 days of the periods. The pasture was divided into nine plots, with one–four plots assigned as the herding area. When the cows grazed in the herding area, the operator maneuvered the vehicle using a transmitter to move them out of the area. The initial reaction (walk away, appear startled, appear interested, back away, or ignore) to the approaching vehicle, flight distance (within one cow-length or more), whether cows escaped from the vehicle or not, and escape gait (walk or run) were classified based on videos recorded during herding. The behavior and location of the cows were observed at 5 min intervals during the time in the pasture. Utilization rates (percentage of grazing time) of the plots were compared with those on days without herding. Throughout the survey, cows initially walked away from the approaching vehicle in 78% of the cases, the flight distance was within one cow-length in 89%, cows escaped from the vehicle in 93%, and when escaping, they walked in 91%. On the first day of herding, these occasions were less frequent (58%, 83%, 84%, and 82%, respectively), but increased on the second day and remained high thereafter. These findings suggest that cows were able to adjust to herding by an unmanned vehicle within a day and respond to the vehicle desirably for the manipulation of grazing distribution with little fear, irritation or discomfort. One-plot herding decreased the use of the herding area from 10.5% to 3.3% (P = 0.001). Two-plot herding decreased the use from 22.3% to 10.4% (P = 0.015) and increased the use of the least-utilized plot from 8.2% to 14.5% (P = 0.021). These findings indicate that robotic herding by an unmanned vehicle has the potential to positively manipulate grazing distribution.