Comparison of virtually fencing and electrically fencing sheep for pasture management

Context. Virtual fencing technology has potential for application in intensive grazing management. However, it is unknown whether the presence of the virtual fence will affect the grazing behaviour of sheep under intensive grazing situations. Aims. This study compared pasture consumption by sheep when pasture access is restricted using either a virtual fence (n = 12) or a conventional electric fence (n = 12), tested over three cohorts. Methods. The sheep were given access to a small section of pasture (8 × 8 m) for approximately 4 h, over a total of 4 days of grazing, being moved onto a fresh plot each day. Within the grazing plot, average pasture dry matter, normalised difference vegetation index (NDVI), and rising plate meter (RPM) height, were measured before and after grazing. NDVI and RPM height were also measured along the fence line before and after grazing. Key results. For within plot measures, there was no effect of treatment on biomass (P = 0.42), pasture height (P = 0.69) or NDVI (P = 0.72). The same was observed for measures taken at the fence line. The results of this study indicated that using a virtual fence to restrict access to pasture to create targeted grazing is as effective as using an electric fence. Conclusions. The similarity in pasture consumption between the groups indicated that the virtual fence does not affect normal grazing behaviour of sheep, nor discourage them from grazing up to the fence line. Further work should be conducted in larger flocks and using automated systems. Implications. Virtual fencing has the potential to be used to restrict sheep access to pasture to create targeted grazing that is as effective as is using an electric fence.