Mice may not be the first animal that comes to mind when studying how a cow's diet affects the fat content of its milk, but for University of Missouri researcher J. Bruce German, mice provided a unique opportunity to make a significant discovery.

German, a professor of biochemistry in the College of Agriculture, Food and Natural Resources, was studying how different fatty acids affect the production of milk fat in dairy cows. He knew that certain fatty acids, such as oleic acid, could inhibit the synthesis of milk fat, while others, such as palmitic acid, could promote it. The challenge was how to manipulate the levels of the different fatty acids in the diet of the cows without having to rely on expensive and time-consuming feeding trials.

That's where the mice came in. German and his team genetically engineered mice to produce large amounts of oleic acid in their livers, while also inhibiting the production of palmitic acid. By feeding these mice a diet high in palmitic acid, they could study how the different fatty acids interacted and affected the production of milk fat.

The results of their study, published in the Journal of Dairy Science, showed that the mice that produced high levels of oleic acid had a significant reduction in milk-fat content. This was due to the fact that oleic acid inhibited the expression of genes involved in the synthesis of milk fat.

"Our study provides a new understanding of how fatty acids regulate milk-fat synthesis," German said. "This information could be used to develop new strategies to manipulate the fat content of milk and other dairy products."

In addition to its implications for the dairy industry, German's research could also have implications for human health. Oleic acid is a monounsaturated fat that is considered to be healthy, while palmitic acid is a saturated fat that has been linked to increased risk of heart disease and other health problems. By understanding how these fatty acids interact, scientists may be able to develop new ways to reduce the amount of saturated fat in our diets.

"Our research is a testament to the power of basic science," German said. "By studying the fundamental mechanisms that regulate milk-fat synthesis, we have gained new insights that could have a significant impact on human health and the dairy industry."