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 new study by Oregon State University researchers and their collaborators.
Many organic and conventional dairies in the study also did not meet standards set by three commonly used cattle welfare programs.
"While there are differences in how cows are treated on organic farms, health outcomes are similar to conventional dairies," said Mike Gamroth, co-author of the study and professor emeritus in OSU's College of Agricultural Sciences. "Few dairies in this study performed well in formal criteria used to measure the health and well-being of cows."
Nearly 300 small dairy farms—192 organic and 100 conventional—in New York, Oregon and Wisconsin participated in the study, which was funded by a $1 million grant from the National Institute of Food and Agriculture in the U.S. Department of Agriculture (USDA).
The five-year project looked at many aspects of dairy cow health, including nutrition, lameness, udder cleanliness, and other conditions. Milk samples were screened for bacteria and common diseases, and farmers were asked about their operations, including the use of veterinarians and pain relief when removing horns from cattle.
Researchers found the following:
- One in five herds met standards for hygiene, a measure of animal cleanliness;
- 30 percent of herds met criteria for body condition, which measures size and weight of cows;
- Only 26 percent of organic and 18 percent of conventional farms met recommendations for pain relief during dehorning;
- Four percent of farms fed calves recommended doses of colostrum, which helps boost their limited immune systems after birth;
- 88 percent of farms did not have an integrated plan to control mastitis, a common disease in dairy cattle;
- 42 percent of conventional farms met standards for treating lameness;
- Cows on organic farms produced 43 percent less milk per day than conventional non-grazing cattle, the study found, and 25 percent less than conventional grazing herds.
Milk from organic and non-organic herds also showed few nutritional differences, researchers found. Organic milk can occasionally contain more omega-3 fatty acids, which may improve heart health. However, those increases come from seasonal grazing and are not present when cattle are fed stored forage, according to Gamroth.