Dairy Cattle Response to a Virtual Fence When Pasture on Offer Is Restricted to the Post-grazing Residual

Abstract

Pasture-based dairy systems rely on the accurate allocation of pasture to both meet livestock requirements and maintain the growth of herbage. Currently, physical fences are used to contain livestock however they can be labor-intensive to shift and maintain. Alternatively, virtual fence (VF) systems offer flexibility and real-time control of livestock location. Pre-commercial neckbands (eShepherd®, Agersens, Melbourne, VIC) emit a warning audio tone (AT) when a cow approaches a VF boundary, paired with an electrical pulse (EP) if the cow continues forward into the exclusion zone (EZ). However, the ability of VF technology to control animal location when pasture is restricted to the previous day's residual, remains unknown. Ten non-lactating Holstein-Friesian dairy cows were trained to use a VF system for 6 days before strip grazing a 1.2 ha paddock of annual ryegrass. Over 10 days the cows grazed eight pasture allocations at a pre-grazing pasture mass of 2,324 ± 81 kg DM/ha (mean ± SE) and post-grazing pasture-mass (post-grazing residual) of 1,649 ± 48 kg/DM/ha with a front VF. The allocations had a physical backing fence that included the fresh allocation and a small area of residual to cater for any GPS drift of the front VF. On each day, with the exception of days 5 and 10, the VF was moved forward, and the cows were provided a new pasture allocation. On days 5 and 10, the VF was not shifted, and cows were only offered the previous allocation's residual pasture. The location of each animal (inclusion, buffer, and exclusion zones) and number of stimuli (AT and EP) delivered were recorded. The number of stimuli delivered between the grazing and hold-off days was similar. Cows spent 89% of time within the inclusion zone (IZ), with significant peaks observed on day 5 and 10. Distance that cows traveled into the EZ reduced across time. There was also evidence of individual variation in the number of stimuli and thus time spent in each zone. Overall, the VF system was successful in containing the dairy cows during strip grazing even when only offered the previous days post-grazing residual.

Current and Future Approaches to Mitigate Conflict between Humans and Asian Elephants: The Potential Use of Aversive Geofencing Devices

“… 11 Colusso et al (2021a) [ 210 ] Australia Experiments conducted with AGDs to evaluate the impact of feed restriction showed that the restriction of food may impact the exclusion of cows from a feed attractant, but later they quickly learnt to avoid receiving the electrical stimuli and stayed within the restricted zone. 12 Colusso et al (2021b) [ 211 ] Australia AGDs were successful in excluding cows from fresh pasture even when they were only provided with post-grazing residuals. However, there were individual variations in the number of stimuli received by animals and time spent in the exclusion zone.…”

Precision technologies to improve dairy grazing systems

“…Cattle are routinely contained with electric fencing of numerous forms within grazing dairy farms. Virtual fencing is an encouraging future technology to implement with grazing dairy cattle because it has the potential to allow for remote improved pasture utilization, and reduced labor ( McSweeney et al, 2020 ; Colusso et al, 2021 ). Virtual fencing provides for boundaries for cattle without using a physical barrier.…”

“…A study in Australia evaluated neckbands for cows (eShepherd, Agersens Pty Ltd.) that produced a warning audio signal and electrical pulse for virtual fencing systems ( Colusso et al, 2021 ). The authors concluded that cows may be contained from fresh pasture forage for 24 h with virtual fencing.…”