CORVALLIS, Ore., Aug. 22, 2014 – Cows raised on organic and conventional dairy farms in three regions of the United States show no significant differences in health or in the nutritional content of their milk, according to a USDA-financed study by three land grant universities. The organic herds also produced 43 percent less milk per day than conventional non-grazing cattle, the study found, and 25 percent less than conventional grazing herds.

Scientists at Oregon State, Wisconsin-Madison and Cornell universities analyzed results of nearly 192 organic dairy farms and 100 conventional operations in New York state, Oregon and Wisconsin in the five-year study, funded by a $1 million grant from USDA’s National Institute of Food and Agriculture (NIFA).

The finding of few nutritional differences between milk from organic and non-organic herds calls into question the previously-challenged claims of nutritional superiority for their products in studies carried out by organic food advocates. “Organic milk can occasionally contain more omega-3 fatty acids, which may improve heart health,” the research found. “However, those increases come from seasonal grazing and are not present when cattle are fed stored forage,” according to Michael Gamroth, professor emeritus in Oregon State’s College of Agricultural Sciences, one of the study’s co-authors.

Gamroth said the study found little difference in the health of cows between conventional and organic farms. Only 26 percent of organic and 18 percent of conventional farms met industry standards for pain relief during dehorning.

The researchers also found more conventional farms (69 percent) used veterinarians than organic dairies (36 percent). Organic dairy farmers often perform their own veterinary work, Gamroth said, because they feel that vets do not always know or follow organic standards for care. Some organic herds in the study also showed a strain of bacteria, commonly known as Strep. ag., that conventional herds eliminated long ago, by using antibiotics.

Organic farms did perform better in some areas of health: cows had fewer hock lesions—injuries to the legs that often form from being housed for long periods. Calves on organic farms were also fed a greater volume of milk and were weaned at an older age than on conventional farms.

Other project collaborators include Pamela Ruegg of Wisconsin-Madison, Linda Tikofsky and Ynte Schukken of Cornell and Charles Benbrook of the Organic Centre in Oregon.


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