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Dairy Farming Old and New

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Got milk? Although the drink is ubiquitous now, it is unclear when ancient farmers started utilizing their cattle for dairy products (as opposed to meat). Now findings published online this week by the Proceedings of the National Academy of Sciences suggest that Britons were harvesting milk as early as 6,000 years ago. Meanwhile, the results of another new study indicate that current practices of cheese making could be improved by genetic engineering: cloned GM cows produce milk with potentially improved processing properties and heat stability.

Richard Evershed of the University of Bristol and his colleagues examined more than 950 broken bits of dirty dishes from 14 archaeological sites in Britain that date to the Neolithic, Bronze Age and Iron Age for evidence of fat. By comparing the ratio of carbon isotopes in the molecules, the scientists identified whether the source of the residue was milk or meat. They found that pieces of pottery from each site held evidence of dairy consumption, though the ages of the milk-marked fragments varied from site to site. Their results, the authors conclude, "provide the first direct evidence, to our knowledge, that the exploitation of animals for milk was already an established practice at the time farming arrived in Britain in the late fifth millennium B.C."

The second study, published online by the journal Nature Biotechnology, hints at what the dairy farm of the future might look like. Gotz Laible and his colleagues at the Ruakura Research Center in Hamilton, New Zealand, altered cells from female dairy cows to include additional copies of two genes that govern production of casein, the predominant milk protein. The cells were fused with donor eggs and implanted in surrogate mothers. Of the 11 cloned cows that survived, nine yielded milk with elevated levels of two casein molecules. Specifically, the milk had eight to 20 percent more beta-casein and nearly twice as much kappa-casein as milk from regular dairy cows. These properties should speed up cheese manufacturing processes and increase their productivity. The authors conclude that "the magnitude of the observed changes highlights the potential of transgenic technology to tailor milk composition in dairy cows." This is the first time that scientists have modified cow's milk solely to improve its quality, instead of to manufacture proteins of pharmaceutical interest. It remains to be seen if the public will agree that milk from a cloned, GM-modified cow still "does a body good."

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