One cloned calf developed normally for six weeks and then mysteriously stopped producing red blood cells and died.

一只克隆牛出生后6周内发育正常，而后莫名其妙地停止产生红血球而死亡。

youdao

For every 100 eggs used, a researcher is lucky to end up with a single cloned calf or a solitary pig in a poke.

ECONOMIST: Cloning around