In an abandoned Japanese village, cows grazing in lush green plains begin to gather when they hear the familiar rumble of the ranch owner's mini-pickup. This isn't feeding time, though.

Instead, the animals are about to be measured for how they're affected by living in radiation - radioactivity that is 15 times the safe benchmark. For these cows' pasture sits near Fukushima, a name now synonymous with nuclear disaster.

The area was once a haven for agriculture with more than 3,500 cattle and other livestock. Ranchers who refused a government order to kill their cows continue to feed and tend about 200 of them. The herds won't be used as food; now science is their mission.