Scientists have already cloned sheep, mice, cattle, goats and pigs. But the world's first cloned cat, announced in the online edition of the journal Nature yesterday, is the first time one of the two great traditional pets, a part of millions of households around the world, has been copied.

The cloned kitten, christened cc, heralds the possible beginning of a lucrative industry to bring beloved family pets back from beyond. She was born at Texas A&M University on December 22.

Ironically, she is not an exact copy of her mother, Rainbow. Her coat is different, because the pattern of colours on multicoloured animals is determined by events in the womb rather than by genes - a reminder that clones may be genetic copies of their parent but are never quite identical.

But the non-scientific appeal of cat cloning is the notion that lost or killed pets could be restored, with at least some of the character and much of the appearance of their predecessors. Researchers at Texas A&M have long attempted to clone dogs, so far without success.

There will be no commercial cat cloning until the procedure becomes more efficient, and until the long-term health of cc is assured. She was cloned from cumulus cells, which surround mammalian eggs before ovulation. This is not an easy cell type to gain access to if the technique were to become widely used. An earlier attempt by the Texas team to clone a kitten from a tom's mouth cells failed.

The embryo from which cc was born was implanted in a surrogate mother and carried to term. Overall, out of 87 cloned embryos transferred to eight female cats, there was one failed pregnancy and one live clone. This is reflective of scientists' continued lack of understanding of what happens during development of cloned embryos.