New Zealand scientists are breeding a herd of cows that produce low-fat milk.

Milk from the cows is also high in health-boosting omega-3 fatty acids and makes butter that spreads as easily as margarine even when chilled, biotechnology company Vialactia said today.

The breakthrough comes after scientists discovered a cow, later named Marge by researchers, carrying the mutant gene in a dairy herd they were testing in 2001, Vialactia chief scientist Russell Snell said.

Vialactia – a subsidiary of the Fonterra Cooperative Group, one of the world’s largest milk companies – bought the cow for $300 NZ (€162) and moved it to a research site.

While she looked like any other Friesian cow, testing revealed that Marge’s milk contained only about 1% fat, compared with about 3.5% for whole milk.

Offspring from the cow also produce low-fat milk, showing the genetic trait is dominant, Snell said.

Scientists have yet to isolate the exact chemical pathway responsible for the naturally produced low-fat milk, Snell said.

“Every now and then nature throws up these sorts of things and it was simply a case of us being in the right place at the right time,” he said.

The company expects the first commercial herd of cows supplying natural low-fat milk and spreadable butter for the market by 2011.