Butter, cheese, yogurt, full cream milk....they are all foods we love to eat. But with the medical warnings of "high fat" and "cholesterol" ringing in our ears, we fear the consequences of eating them.

But now, thanks to these cows, we may be able to eat dairy products literally to our heart's content.

Dairy pastures are high in polyunsaturated oils, which are broken down by microbes in the cow's first stomach, leaving the harder saturated fats.

So CSIRO's Dr. Suresh Gulati devised a special feed supplement for the cows, a mixture of canola and soybeans, to see if it would lower the saturated fat in their milk.

In laboratory experiments that recreated the environment of a cow's stomach, the additive created a coating of protein around the oil, preventing the microbes attacking the polyunsaturates.

The next stage was to feed it to the cows.

"What we do is feed a small supplement every day in conjunction, whether they're on pasture or whether is a feed lot. It's analogous to humans having supplements of vitamins and iron"

The result was the same as in the laboratory; The polyunsaturated fats were carried through to the small intestine and into the meat and milk without being converted into saturated fat. It meant a reduction in the saturated fat in their milk.

And when products made from that milk were consumed by humans, in a trial by CSIRO's Division of Human Nutrition, the result was a significant reduction in the type of cholesterol associated with heart disease

And there is a valuable bonus. Because it's the saturated or hard fats in butter that makes it unspreadable, by getting rid of them it means more spreadable butter.