A team of US and Japanese researchers have declared that milk and meat from cloned cattle are likely to be safe for human consumption, although stressed that research in this area was still very much in its infancy, Tom Armitage reports.
Researchers cloned two Japanese Black beef bulls and four Holstein dairy cows, using somatic cell nuclear transfer - the same technique used to clone Dolly the sheep over nine years ago - bringing the world's total cloned animal count to around 1,000.
Japanese Black beef bulls were selected for the study, as they are renowned for their meat marbling effects, while Holstein dairy cattle are said to produce high quality milk yields.
Scientists at the University of Connecticut's Centre for Regenerative Biology and the Kagoshima Prefectural Cattle Breeding Development Institute in Japan compared the meat and milk of the cloned animals to that produced by animals bred naturally of the same age and breed.
After analysing the cloned animals' levels of protein, fat and other variables in their milk, they concluded that there were "no significant differences" when compared to the milk of normal dairy heifers.
"The production of each milk protein constituent involves the elaborate regulatory function of many proteins and enzymes, and any abnormal gene expression would likely be reflected by imbalances in the constituents of milk," said the report, published earlier this week in the Proceedings of the National Academy of Sciences journal .
Conversely, one hundred meat quality criteria were examined and 90 per cent of these showed no significant variation between cloned and naturally bred beef and although the levels of fat and fatty acids were much higher in the cloned variety, both beef and milk were lauded for being "within the normal range of beef and dairy products approved for human consumption".
Although the tests suggested that the genes of the cloned animals were no different to their natural counterparts and were functioning normally, cloning critics, including some consumers and food safety regulators, have raised concerns that eating the produce of cloned animal be detrimental to human health - after a number of previous cloning technology experiments produced a string of birth defects.
The US Food and Drug Administation's (FDA's) veterinary authority is set to deliver a verdict on whether meat and milk from cloned animals are fit for human consumption and has, in the meantime, urged food producers to prevent products from cloned animals from entering the supply-chain.
Lead scientist Xiangzhong Yang of the University of Connecticut suggested that his team's findings would serve as "guidelines" for further studies, involving a number of clones from different genetic backgrounds.