Certain feeding methods for cattle can result in healthier beef and milk. Recent field research has shown that pastured cows produce more healthful products than those finished on harvested forages, hay or silage.

A study conducted by Iowa State University researchers documented the concentrations of conjugated linoleic acid (CLA) in beef and milk from farms in northeast Iowa and southwest Wisconsin. CLA is a fatty acid thought to help prevent cancer, diabetes and obesity. Beef and milk are two of the main sources of CLA in the human diet.

The study involved four beef and 12 dairy farms. Each farm was visited once per month. At each visit, the cattle’s diet was recorded and milk samples were taken. Beef samples were taken when the finished cattle were processed. The milk and beef samples were analyzed for CLA content.

CLA was measured as a percentage of the total fatty acids found in the beef or milk. Of the four beef producers in the study, one used some pasture feeding for the cattle.
The other three used only harvested forages. The cattle that were grazed had from 0.34 to 0.46 percent CLA. The cattle that were only fed harvested forages had from 0.23 to 0.33 percent CLA.

Among the dairy farms, the average concentrations of CLA over the course of the study were 0.35 percent in Iowa and 0.27 percent in Wisconsin. The CLA concentrations fluctuated throughout the year, with the highest concentrations being observed in May and June, prime grazing months. The winter months, when harvested forages were used, produced the lowest CLA concentrations. In June, one farm in Iowa and one in Wisconsin had average CLA concentrations of over 1.3 percent.

“This study helps confirm on the farm what has already been found to be true in a laboratory,” says Allen Trenkle, Distinguished Professor of Agriculture at Iowa State University. “I think there’s a potential of these products having greater value if they can maintain their identity on the market.”

For more information about this research, visit www.iowabeefcenter.org