HARTFORD, Conn. - Xiangzhong "Jerry" Yang, a stem cell scientist who successfully cloned the first farm animal in the United States, has died after a long battle with cancer. He was 49.

Yang, director of the Center for Regenerative Biology at the University of Connecticut, died Thursday at Brigham and Women's Hospital in Boston, school spokesman David Bauman said Friday.

In 1999, Yang put UConn on the world's scientific map when a Holstein named Amy was born in Storrs. She was the first cloned farm animal in the United States. The world's first cloned animal was Dolly the sheep, created in 1996 in Scotland.

But Yang died before achieving one of his dreams: the cloning of a human embryo for potentially lifesaving stem cells.

Escaping starvation in rural China as a baby in a village about 300 miles south of Beijing, Yang was placed in the prestigious Beijing Agricultural University, where his high test scores earned him a coveted opportunity to pursue a graduate education in the United States.

Yang proved that early reports that clones would age prematurely were false. The Food and Drug Administration relied heavily on Yang's work when it found meat and dairy products from cloned farm animals were safe to eat and drink.

"Jerry was one of the greatest scientists and cloning pioneers of our time," Dr. Robert Lanza, chief science officer at Advanced Cell Technology of Worcester, a biotech company which has pursued creating stem cells through cloning, told The Hartford Courant. "He was a really great man who struggled to his last hours to better the world and to advance the scientific cause."