Virtual fencing technology to intensively graze lactating dairy cattle. I: Technology efficacy and pasture utilization

Virtual fencing is promoted as the next advancement for rotational grazing systems. This experiment com-pared the capacity of conventional temporary electric versus virtual fencing to contain a herd of 30 lactating dairy cows within the boundaries of their daily pasture allocation (inclusion zone). Cows were moved each day to a new rectangular paddock that was divided cross-wise into an inclusion and exclusion zone by a single linear electric (first 10 d) or virtual (second 10 d) front-fence. A 3-d virtual fence training period separated the 2 treatments. Virtual fences were imposed using a pre -commercial prototype of the eShepherd virtual fencing system (Agersens Pty Ltd.). Neckband-mounted devices replaced the visual cue of an electric fence with benign audio cues, which if ignored were accompanied by an aversive electrical stimulus. Cows learned to respond to the audio cues to avoid receiving electrical stimuli, with the daily ratio of electrical to audio signals for individual cows averaging (+/- standard deviation) 0.18 +/- 0.27 over the 10 d of virtual fence deployment. Unlike the electric fence, the virtual fence did not fully elimi-nate cow entry into the exclusion zone, but individual cows were generally contained within the inclusion zone >= 99% of the time. Pasture depletion within the inclu-sion zone reduced the efficacy of the virtual fence in preventing cows from entering the exclusion zone, but the magnitude of this effect was insignificant in practi-cal terms (i.e., increased time spent in the exclusion zone by <= 28 s/h per cow). This highlights the potential for virtual fences to control grazing dairy cow move -ment even when pasture availability is limited (i.e., 1 kg of dry matter/cow above a target residual of 1,500 kg of dry matter/ha), but requires confirmation under longer and more complex virtual fencing applications. Within each treatment period, uniform daily pasture utilization (% of pasture consumed above a target residual of 1,500 kg of dry matter/ha) within inclusion zones indicates that cows did not avoid grazing near electric or virtual front-fences. Overall, this study demonstrated a suc-cessful simple application of this virtual fencing system to contain a herd of grazing lactating dairy cows within the boundaries of their daily pasture allocation.

Automated summary

Virtual fencing is promoted as an advancement for rotational grazing systems. This study compared conventional temporary electric fencing with virtual fencing to contain a herd of dairy cows, showing that virtual fencing can effectively control the cows' movement, even though its efficacy may decrease after pasture depletion.