GM cheese from cow clones

" The increases observed in our study represent large changes that would translate into substantial economic gains "
NZ researchers

The researchers in Hamilton say their herd of nine transgenic cows make highly elevated levels of milk proteins - called casein - with improved processing properties and heat stability.

Cows have previously been engineered to produce proteins for medical purposes, but this is the first time the milk itself has been genetically enhanced.

The scientists hope the breakthrough will transform the cheese industry, and - if widened - the techniques could also be used to "tailor" milk for human consumption.

But opponents of GM foods continue to doubt whether such products will be safe.

'Substantial gains'

The researchers, led by Goetz Laible, engineered cells in the laboratory to overproduce casein proteins. The cells were then fused with cow eggs.

The resulting embryos were transferred into recipient cows, and 11 transgenic calves were born. Nine were found to produce the enhanced milk.

One protein, called kappa-casein, increases heat stability in the cheese-making process.

The other, beta-casein, improves the process by reducing the clotting time of the rennet, which curdles the milk.

It also increases the expulsion of whey, the watery part of milk which remains after the cheese has formed.

The cows are now producing milk with 8-20% more beta-casein, and double the normal amount of kappa-casein.

Reporting their findings in the journal Nature Biotechnology, the scientists said that controlling levels of the two proteins could offer big savings for cheese manufacturers.

"When projected on to the production scale of the dairy industry, the increases observed in our study represent large changes that would translate into substantial economic gains," they wrote.