The ability of ewes with lambs to learn a virtual fencing system

Abstract

The Nofence technology is a GPS-based virtual fencing system designed to keep sheep within predefined borders, without using physical fences. Sheep wearing a Nofence collar receive a sound signal when crossing the virtual border and a weak electric shock if continuing to walk out from the virtual enclosure. Two experiments testing the functionality of the Nofence system and a new learning protocol is described. In Experiment 1, nine ewes with their lambs were divided into groups of three and placed in an experimental enclosure with one Nofence border. During 2 days, there was a physical fence outside the border, during Day 3 the physical fence was removed and on Day 4, the border was moved to the other end of the enclosure. The sheep received between 6 and 20 shocks with an average of 10.9 ± 2.0 (mean ± SE) per ewe during all 4 days. The number of shocks decreased from 4.38 ± 0.63 on Day 3 (when the physical fence was removed) to 1.5 ± 0.71 on Day 4 (when the border was moved). The ewes spent on average 3%, 6%, 46% and 9% of their time outside the border on Days 1, 2, 3 and 4, respectively. In Experiment 2, 32 ewes, with and without lambs, were divided into groups of eight and placed in an experimental enclosure. On Day 1, the enclosure was fenced with three physical fences and one virtual border, which was then increased to two virtual borders on Day 2. To continue to Day 3, when there was supposed to be three virtual borders on the enclosure, at least 50% of the ewes in a group should have received a maximum of four shocks on Day 2. None of the groups reached this learning criterion and the experiment ended after Day 2. The sheep received 4.1 ± 0.32 shocks on Day 1 and 4.7 ± 0.28 shocks on Day 2. In total, 71% of the ewes received the maximum number of five shocks on Day 1 and 77% on Day 2. The individual ewes spent between 0% and 69.5% of Day 1 in the exclusion zone and between 0% and 64% on Day 2. In conclusion, it is too challenging to ensure an efficient learning and hence, animal welfare cannot be secured. There were technical challenges with the collars that may have affected the results. The Nofence prototype was unable to keep the sheep within the intended borders, and thus cannot replace physical fencing for sheep.

Social influence on the effectiveness of virtual fencing in sheep

“…The behaviours of the sheep may also have been affected by the initial adaptation period to the VF. Other studies that have looked at implementing virtual fencing in sheep have not looked at the implementation of the technology over a long period of time and have not been able to look into impacts on normal behaviour (Brunberg et al, 2017;Brunberg, Bøe & Sørheim, 2015;Jouven et al, 2012). In our previous study (Marini et al, 2018a), it was found that behavioural time budgets were affected after the virtual fence was removed, through a decrease in lying behaviour, but not during the fence implementation.…”

“…Initial studies in sheep have shown that they readily learn to respond to an audio cue to avoid an electrical stimulus when trained individually (Marini et al, 2019;Marini et al, 2018a), a fundamental component required for virtual fencing to be ethically acceptable (Lee, Colditz & Campbell, 2018). There have been few studies that have evaluated group responses to the virtual fence and whether a group of sheep could be trained in a paddock environment (Brunberg et al, 2017;Jouven et al, 2012). These studies found mixed success in containing animals within a paddock.…”

Peer Review #3 of "Social influence on the effectiveness of virtual fencing in sheep (v0.1)"

“…The behaviours of the sheep may also have been affected by the initial adaptation period to the VF. Other studies that have looked at implementing virtual fencing in sheep have not looked at the implementation of the technology over a long period of time and have not been able to look into impacts on normal behaviour (Brunberg et al 2017;Brunberg et al 2015;Jouven et al 2012). In our previous study (Marini et al 2018a), it was found that behavioural time budgets were affected after the virtual fence was removed, through a decrease in lying behaviour, but not during the fence implementation.…”

Sensing solutions for improving the performance, health and wellbeing of small ruminants

“…To preserve batteries when the animals are inside a barn, a bluetooth beacon is used to switch-off the collars. First results in Norwegian White and Spael sheep (Brunberg et al, 2013(Brunberg et al, , 2017, showed strong differences in learning ability between animals (9 out of 24, 37.5%) and that the fixed position of virtual boundaries are key for the sheep understanding. The NoFence company claims that the collars are also adequate for free-grazing goats.…”