Cloning pioneer Hwang Woo-seok has sent a cow resistant to mad cow disease to Japan for joint study.

An animal hygiene think tank will conduct joint studies on the animal's resistance to the mad cow virus and any harmful effects to humans.

Hwang's Seoul National University team bred four such cows in 2003 by normalizing the variant prion protein that causes the disease.

Soon after, Japan proposed a joint study on the cows.