Cows put on diet to block cholesterol-causing fats

American university researchers have put dairy cows on a diet that blocks a significant amount of cholesterol-elevating fat from their milk.

Two professors at the University of California hope their findings will lead to a healthier milk being sold in supermarkets within a year.

Using a heat-treated supplement of whey protein and oil, the professors thwarted a bovine digestive twist that takes feed high in unsaturated fat and transforms it into unwelcome saturated cholesterol in the cow's milk.

The food supplement prevents that conversion by shielding the unsaturated fats from the action of micro-organisms and protozoa in the cow's largest stomach, known as the rumen, said researchers.

High levels of saturated fats in diets in many developed countries - including New Zealand - have been linked to elevation of cholesterol and to heart disease.

Professor Moshe Rosenberg, a dairy specialist in the university's department of food science and technology, and Ed DePeters, an animal science professor, ran multiple 21-day tests involving more than 1500 milk samples for a year. Researchers recorded up to an eight-fold increase in the levels of unsaturated fats in cows' milk.

The feed formula did not require approval by the United States Food and Drug Administration because the processes and food used were already permitted, said Professor Rosenberg.

The researchers have now moved on to pilot projects followed by larger-scale milk and feed production.

"This is a technology that can be used commercially on any dairy [farm] in the USA," said Professor DePeters, noting that it was developed without genetic modifications and using ingredients safe for consumers.

Industry experts said acceptance by dairy farmers would depend in large part on acceptance by consumers.

"The dairy farmer is going to have to work with the person or the company that buys the milk," said Joe O'Donnell, executive director of the California Dairy Research Foundation in Davis.

"If you have a dairy farmer selling a product to ... the retail marketplace [the retailer], is going to have to do the market research and determine how much consumers are going to be willing to pay for a value-added product."

The milk would be healthier: milk, cheeses and even meat with lower saturated fats would not translate into fewer calories, but the researchers said the benefits, would be in improved cardiovascular health for some consumers.

Dr O'Donnell, who has a doctorate in nutrition, said cardiovascular health was highly complex, with many factors at play - human genetics among the largest.

- NZPA