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

Abstract

Virtual fencing is promoted as the next advancement for rotational grazing systems. This experiment compared 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 crosswise into an inclusion and exclusion zone by a single linear electric (first 10 d) or virtual (second 10 d) frontfence. A 3-d virtual fence training period separated the 2 treatments. Virtual fences were imposed using a precommercial 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 eliminate cow entry into the exclusion zone, but individual cows were generally contained within the inclusion zone ≥99% of the time. Pasture depletion within the inclusion 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 practical 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 movement 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 successful simple application of this virtual fencing system to contain a herd of grazing lactating dairy cows within the boundaries of their daily pasture allocation.

A Case Study on the Use of Virtual Fencing to Intensively Graze Angus Heifers Using Moving Front and Back-Fences

“…Thus, the present study compared the effectiveness of virtual fencing technology to contain Angus heifers within grazing cells defined by semi-permanent electric side-fences and virtual front and back-fences to heifers contained in cells defined only by electric fencing. We predicted that the technology will limit cattle access to fresh pasture in the excluded area beyond the virtual fences with 99% efficacy (which is comparable to efficacies reported in dairy cattle, Lomax et al, 2019;Langworthy et al, 2021), resulting in similar pasture utilization and live weight changes between the groups.…”

“…Pre-and post-grazing pasture biomass estimates were taken immediately before and after each 3 day grazing allocation using an Ag Hub TM F200 electronic rising plate meter (Farmworks Systems, Feilding, New Zealand). In each cell, ∼100 measurements of compressed pasture height were taken in a zigzag transact, averaged, and converted into pasture biomass (kg of DM/ha) using the following site-specific calibrated equation: This equation was derived from Langworthy et al (2021) and was created using perennial ryegrass swards taken in the same month of the previous year and at the same site as the present experiment. Estimated pasture intake for each group of heifers were then calculated from these data.…”

“…Virtual fencing is an emerging technology that contains and controls grazing cattle using sensory cues rather than physical fences. The technology comprises a neckband-mounted device that delivers an audio cue when the animal nears a virtual boundary that has been set via global positioning system (e.g., Campbell et al, 2019;Lomax et al, 2019;Langworthy et al, 2021). An electrical stimulus is delivered by the device if, following the audio cue, the animal walks beyond the virtual boundary, but not if it stops walking or turns back.…”

“…In both cases, administration of the aversive electrical stimulus following the undesired behavior (i.e., physical interaction with the electric fence or progressing beyond the virtual boundary after an audio cue) results in the behavior becoming less likely in the future. Cattle quickly learn the association between audio cue and a pending electrical stimulus, and over time increasingly respond to the audio cue alone (Campbell et al, 2019;Langworthy et al, 2021). Thus, virtual fencing affords a flexibility to grazing management that has the potential to revolutionize pastoral livestock production.…”

“…Virtual fencing could remove some of these barriers and facilitate the intensification of grazing management for grazing beef cattle. Australian research using an experimental prototype of virtual fencing technology (eShepherd R ) shows that beef cattle in extensive grazing systems are successfully maintained behind a moving virtual front-fence (Campbell et al, 2017) and the technology can be used to exclude cattle from environmentally sensitive areas (Campbell et al, 2018(Campbell et al, , 2020, while dairy cattle in intensive grazing systems are prevented from accessing fresh pasture beyond a virtual front-fence (Lomax et al, 2019;Langworthy et al, 2021). The application of virtual fencing technology to intensively graze beef cattle has not been demonstrated, however, nor has it been applied to manage sophisticated grazing regimes such as those involving more than one virtual boundary.…”