Heart-healthy milk on tap

The milk industry churns over new findings in the US that claims a simple supplement can dramatically boost the content of unsaturated fatty acids in cows' milk.

Developed by food scientists at the university of California, the new cattle-feed supplement, based on naturally occurring proteins, could open the way to provide dairy-food processors with the ability to modify various food qualities, such as the spreadability of butter and the flavour of cheese.

"We are excited about the health benefits this new technology will offer to consumers and the options it will give to dairy-food processors,"​ said Moshe Rosenberg, at the department of food science and technology.

The quest to cut saturated fats in our modern diet is largely because these fats have been implicated in contributing to a higher risk of cardiovascular disease and high cholesterol in humans. Milk, butter and meats have long been known to contain high levels of saturated fats and are in the first line of fire when actions are promoted to reduce saturated fats. Rosenberg's development could offer the food industry a neat solution to the problem.

The dairy specialist developed the new feed supplement along with Ed DePeters, a UC Davis animal science professor who specialises in the nutrition of dairy cows.

Cows commonly eat a variety of plant-based feeds that contain various levels of vegetable oils, naturally high in unsaturated fats. However, during rumination, researchers discovered decades ago that microorganisms that live in the rumen - the largest of four compartments in the cow's stomach - are the culprits responsible for converting unsaturated fats into saturated fats.

"The rumen is a large anaerobic fermentation vat. These microbes metabolise the unsaturated fats as they pass through the rumen, which involves converting the unsaturated fatty acids into saturated fats in a process known as 'biohydrogenation',"​ explained DePeters. "Its been clear for decades that in order to reduce the saturated fats in milk and meat, we would have to protect the unsaturated dietary fats from these microbes in the rumen."​

During the 1970s, efforts were made to protect the unsaturated fats against modification by mixing chemical additives with the feed. Those supplements, however, included toxic chemicals, such as formaldehyde banned in several countries. In the 1980s, other researchers attempted to prevent modification of unsaturated fats by mixing in soap-like formulations with the cattle feed. That technique had only limited success in preventing unsaturated-fat modification in the rumen.

Unlike the earlier methods, the supplement devised by Rosenberg and DePeters relies on proteins that occur naturally in milk and other foods, without using any synthetic chemicals.'By taking advantage of the unique properties of proteins, the researchers were able to form complexes between those proteins and substances called lipids, which are high in unsaturated fatty acids,'​ said a statement from California university this week.

These complexes protect the lipids against modification by the microorgnisms that live in the rumen. As a result, the unsaturated fats pass unmodified through the rumen; eventually enter the cow's intestine for digestion, where the unsaturated fatty acids are then available for absorption into the blood stream; and finally are presented to the mammary gland, where the milk is produced.

During feeding trials, the researchers mixed the supplement with the cows' normal feed. Within less than three days, they recorded as much as an 800 per cent increase in the proportion of specific unsaturated fatty acids, such as linolenic acid, in the cows' milk.

Although the supplement's effects have only been studied on the fatty-acid composition of milk, the researchers indicate that it might have similar benefits in reducing the level of saturated fats in meat.

"In addition, this same protein-based, rumen-protected supplement could be used as an efficient system for delivering bio-active compounds and medicines to cows and other animals,"​ concluded Rosenberg​.