Got grass?

The U.S. Department of Agriculture has imposed strict new standards for what kind of milk qualifies as organic: Cows must get plenty of fresh grass and spend at least four months a year grazing in pastures.

The rules, which will go into effect June 17, are aimed at standardizing industry practices and easing consumer concerns about how the milk they buy is created.

Current rules require milk marketed as organic to come from cows whose feed was grown without chemical fertilizers, pesticides or genetically modified seeds. Herds can’t be treated with hormones or antibiotics.

The new rules seek to close loopholes that had allowed some of the country’s largest feedlots to sell their milk as organic, even though their herds rarely grazed in fields. Bovines are natural grazers that have been known to contract digestive ailments from grain. Farmers will have to ensure that at least 30% of their cows’ diet comes from pasture grass during the mandatory grazing season.

Farmers in more temperate regions — such as California and the Southeast — will be expected to let them eat au natural far longer than the minimum 120 days.

Organic activists, however, were cautiously hopeful.

“The success of this rule will depend on the USDA enforcing the bigger picture, of cows being on pastures,” said Alexis Baden-Mayer, political director of the policy group Organic Consumers Assn.