Forgive my ignorance, but whats the point? It would be a lot more expensive and time consuming to rip trenches all through your paddocks, lay an underground wire and collar every single one of you livestock. What happens when a calf walks over the wire and can't feel it due to not being collared while the cow would go stupid trying to get it.
Maybe a fence isn't technological/expensive enough.
Besides, who wants to have to worry about sticking big collars on 1000 head of cattle (I know its in the experimental stage but I can't see the point in any possible advancements)