Virtual, moving fences controlled from a laptop could one day herd cattle to fresh fields for grazing, a roboticist told the MobiSys 2004 conference in Boston, Massachusetts, on Sunday.

A farmer would control multiple herds from a single server at home as if they were playing a video game, said Zack Butler, of Dartmouth College in Hanover, New Hampshire.

Although static virtual fences already keep dogs inside yards in affluent US neighbourhoods, no-one has attempted a moving virtual fence before, nor attempted to apply the idea to large herds of animals. “Basically we download the fences to the cows,” says Butler. “We say: ‘Today stay here, tomorrow go somewhere else.”

Butler and his colleagues have written software that transmits the chosen GPS co-ordinates of a virtual fence to head-collars worn by the cows in the field.

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