David Pitman is a third-generation poultry grower, raising chickens and turkeys with his brother and parents on a property east of Fresno that his grandfather founded in 1954. They’re independent farmers—instead of raising birds for a corporation, they sell directly to wholesalers and stores—and their farming style reflects that freedom. They buy turkeys from a variety of breeds, feed them organic grains, and let them wander over pasture, choices that make the final product very different from the broad-breasted birds raised at industrial scale by national meatpacking companies.

In one way, though, both products are more alike than they are different. The Pitmans have always raised their birds without putting antibiotics in their feed. Now the rest of the turkeys—and chickens and cattle and pigs—raised in the United States are moving that way thanks to federal regulations that went into effect on January 1, 2017.

The turkeys that will appear on tables across the country this week were hatched after those rules became final, which makes this, aspirationally at least, the first antibiotic-free Thanksgiving. But farmers such as Pitman who have done without the drugs for years say that, as desirable as that may be—for animals, and also for people threatened by the antibiotic-resistant bacteria that result—it’s harder than it looks.

The movement to raise meat without routine antibiotics was started three years ago by Perdue Farms, the fourth-largest chicken company in the United States. Other poultry companies followed, making “no antibiotics ever” chicken commonplace now. But “turkeys are much more difficult, probably 10 times more difficult, to raise antibiotic-free than chickens are,” Pittman says. “Any little thing throws them off.”

Maybe a little background is in order. Antibiotics came on the market in the 1940s, and before that decade was over, farmers had begun adding low doses of the drugs to animal feed, first to make livestock put on weight faster and then to protect them from diseases as growers packed more animals onto farms.