Extra fat in a cow’s diet during her last six weeks of pregnancy could help her newborn calf fare better in cold temperatures.

Preliminary results by scientists with the USDA’s Agricultural Research Service showed for the first time that fat in the cow’s diet may have an important role in a newborn calf’s ability to maintain its body heat. An estimated 95,000 calves die each year due to cold stress, but that number could be higher in this year’s bitter winter temperatures.

Researchers added safflower with high concentrations of linoleic and oleic fatty acids to the diets of 12 cows for 53 days prior to calving. Another 11 ate a standard feed ration.

For the first five hours after birth, the calves stayed at room temperature. Then they were put in a room kept at 32 degrees Fahrenheit. During the 140-minute experiment, body temperatures of calves from normally fed cows fell one-third of a degree more than calves whose mothers ate the extra fats.

The effect of this temperature drop on calf survival is still under study. But calves born to cows on the high-fat diet had more “brown” fat. Brown fat surrounds organs such as the kidneys and helps the animals generate body heat immediately after birth.

Researchers are repeating the experiment to confirm the first year’s results.

Other supplements such as rice bran and soybean oil also contain fatty acids in different combinations, but their effect on calf heat production is unknown.

Scientific contact: Robert Bellows, USDA-ARS Fort Keogh Livestock and Range Research Laboratory, Miles City, Mont., phone (406) 232-4970