John McNamara, animal science professor, and Jennifer Sumner, Washington State University doctoral student and postdoctoral research associate, have demonstrated that chromium in the diet changes the metabolism of body fat in dairy cattle by stimulating the expression of certain genes while simultaneously decreasing the expression of others.

Though it had long been known that the mineral chromium is required in the diet for good health in both animals and humans, the specific role it played in fat metabolism and milk production had not been described until now.

Adipose tissue is key

For more than 20 years, McNamara and his team have been working to identify genetic factors related to efficient milk production in dairy cattle. Knowing that adipose (fat) tissue plays an active role in successful reproduction and lactation, they centered their studies on identifying the metabolic functions of body fat. One of their main goals was to identify cows that gained neither too much nor too little weight during pregnancy and lactation.

When cows store too much body fat, energy is diverted away from milk production and instead goes toward storing more fat, McNamara says. "Yet if a cow does not store enough fat — or loses it too quickly — her immunity is impaired, causing inefficient production and leading to diseases like ketosis, milk fever and mastitis. Adipose tissue, in addition to being a major energy storage organ, is also a source of several powerful hormones that control food intake, inflammation and immunity."

Source: Dairy Herd Management