SCIENTISTS in China have created genetically modified cows that produce ''human'' milk.
The scientists successfully introduced human genes into 200 dairy cows to produce milk with the same properties as human breast milk.
The scientists behind the research believe that milk from herds of genetically modified cows can provide an alternative to human breast milk and formula milk for babies.
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Critics of the technology and animal welfare groups reacted angrily to the research, questioning the safety of milk from genetically modified animals and its effect on the animals' health.
Ning Li, the scientist who led the research and director of the State Key Laboratories for agro-biotechnology at the China Agricultural University, insisted that the genetically modified milk would be as safe to drink as milk from ordinary dairy cows.
''The milk tastes stronger than normal milk,'' he said. ''Within 10 years, people will be able to pick up these products at the supermarket.''
Helen Wallace, director of GeneWatch UK, a biotechnology monitoring group, said: ''We have major concerns about this research. There are welfare issues with genetically modified animals as you get high numbers of stillbirths.
''There is a question about whether milk from these cows is going to be safe for humans and it is really hard to tell that unless you do large clinical trials like you would with a drug.''
Professor Li and his colleagues said they had produced a herd of about 200 cows that were able to produce human-like milk.
The researchers used cloning technology to introduce human genes into the DNA of dairy cows before the genetically modified embryos were then implanted into surrogate cows.
During two experiments by the Chinese researchers, which resulted in 42 transgenic calves being born, just 26 of the animals survived.
Writing in the Public Library of Science One, a scientific peer-reviewed journal, the researchers said they created cows that produced milk containing a human protein called lysozyme, which helps protect infants from bacterial infections during their early days.
The researchers have also created cows that can produce another protein from human milk, lactoferrin, which helps to boost the number of immune cells in babies.