Having disregarded a state instruction to kill cattle left behind in areas near the crisis-hit Fukushima Daiichi nuclear plant, some local farmers have been struggling to keep about 430 cows within a 20-kilometers radius of the complex exposed to radiation.

The instruction was issued two months after fuel meltdowns at the plant in northeastern Japan were triggered by a massive earthquake and a tsunami on March 11, 2011, for about 3,500 cows kept within the area adjacent to the Fukushima Daiichi complex.

Regarding their cows as "family members," some farmers ignored the instruction, while others who followed it say they still suffer psychologically. The central government allowed cattle breeding in the 20-km zone in 2012, but shipments are still banned.

Keiji Okada, a professor of veterinary science at Iwate University and a researcher of animals exposed to radiation, has been taking blood and urine samples from cows at a couple of farms in the zone to see if there are any genetic abnormalities in them.

One farmer who is cooperating with the research is Fumikazu Watanabe, a 60-year-old local cattle farmer, in the town of Namie, several kilometers from the Fukushima plant.

Watanabe said he wants to protect his 50 cows "until they die a natural death just like human parents protect their children."

Before returning to Namie in October last year after evacuation orders for some parts of the town were lifted, Watanabe used to shuttle between the farm and his shelter, which was about 50 km away, by applying for special entry permission to take care of his cows.

Radiation levels at Watanabe's farm stand at 15 to 20 microsieverts per hour, the highest among the seven farms where the 430 cows are kept, but his cows are "so far in perfect health," Okada said.