Gene-Modified Cow Makes Milk Rich in Protein, Study Finds

Scientists have altered the genes of a dairy cow to produce milk that’s rich in a protein used in numerous food products and lacking in a component that causes allergies in humans.

Using a process called RNA-interference that turns certain genes on or off, scientists from New Zealand produced a cow whose milk had increased casein, a protein used to make cheese and other foods, and almost no beta-lactoglobulin, a component in milk whey protein that causes allergies. The female calf was also born without a tail, according to the report today in the journal Proceedings of the National Academy of Sciences.

The study can be seen as a proof-of-concept that tinkering with nutritional content genetically is possible, said William Hallman, director of the food policy institute at Rutgers University. More testing will be needed to determine the milk’s full dietary content, and scientists must consider the effects of breeding gene-altered animals, he said. The field has been controversial because of safety and environmental concerns.

“Could you clone a breeding stock that would allow for a herd with milk of this type?” Hallman, who wasn’t involved in the study, said in a telephone interview. “There are lots of issues about what might happen in the next generation.”

Today’s research represents a road map for other groups that may wish to knock out proteins, and not just in milk, he said.

Dairy Economics

Farmers in the U.S. earned about $35 billion in 2011 from dairy sales, said Christopher Galen, a spokesman for the National Milk Producers Federation.

Aside from the hypoallergenic qualities, the genetically modified cow’s milk may also be valuable for its higher content of casein. The milk protein is used in a range of food products, including cheese, thickening agents in soups, salad dressings and whipped toppings. It’s also used in adhesives, cosmetics and some pharmaceuticals, Hallman said.

“In terms of dairy economics, casein is the most profitable part of the milk,” he said.

Ordinarily, the proportion of whey to casein in the milk from dairy cows is 21-to-79, according to the paper. The milk from the genetically altered cow had a ratio of 4-to-96, according to a paper. That’s probably due to a 96 percent reduction in beta-lactoglobulin, or BGL, the paper said.

Milk Allergies

Beta-lactoglobulin is produced in cows and other ruminant animals, but isn’t found in human milk. About 2 to 3 percent of infants in developed countries are allergic to cow’s milk proteins in the first year of life, according to the study.

Taillessness is a congenital condition in cows, the researchers wrote. More research will need to be done to determine if the calf’s taillessness is related to the gene silencing technique used to change the cow’s milk.

Tests now need to be done to see whether removing BLG really does help those with allergies and whether the genetic change harms the animal, according to the paper, written by researchers from New Zealand’s AgResearch, a government-owned research institute, and the University of Waikato, both based in Hamilton, New Zealand.

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