Farmers swap fences for GPS tracking collars

New technology is being used by farmers in Oxfordshire for the first time to control livestock without putting up fences.

Sam Sandberg uses satellite tracking collars on her cattle at Lyneham Heath Farm near Chipping Norton and said they have increased the amount of land that could be grazed.

The animals wear battery-operated devices that play specially created sounds, then emit an electrical pulse, if they stray across a virtual boundary.