Why invisible fencing?
Invisible fencing is an innovation that allows the control of cattle movement without needing physical barriers. In open areas, cattle can be fitted with a Geographical Positioning System (GPS) which will signal when a cow approaches a boundary.
Under trees in a wood pasture, due to the intermittent GPS signal, an alternative method is to bury an electric cable in the soil surface that emits a shortwave radio signal which is sensed by a transponder on a cattle collar. The transponder emits a noise as a cow approaches the boundary and, if she does not turn back, it provides an electric pulse similar to an electric fence. At Epping Forest, each collar also includes a GPS sensor which helps to locate the cattle.