Tyson Foods Inc has removed gentamicin, a key antibiotic for human use, from company hatcheries, the company told Reuters on Tuesday.

Arkansas-based Tyson, the nation's largest chicken producer, said the drug and other antibiotics have not been used at its 35 hatcheries since Oct. 1, 2014. The company had not previously given details of what drugs were used at the hatcheries, where chicks are born and kept briefly before being moved to poultry farms.

Gentamicin is a member of an antibiotic class considered "highly important" in human medicine by the federal Food and Drug Administration.

The poultry industry has long been under pressure to stop feeding medically important antibiotics to otherwise healthy livestock. Meat companies have used the drugs both to stave off disease and to promote more rapid growth.

Last week, McDonald's Corp said its U.S. restaurants will gradually stop buying chicken raised with antibiotics vital to fighting human infections. Tyson Foods is a major chicken supplier to McDonald's.

Tyson told Reuters this week it is also testing alternatives to medically-important antibiotics for use on the farms that house its chickens after they leave the hatcheries. It says it does not use antibiotics for growth promotion on the farms, but does use them, according to its website, "when prescribed by a veterinarian to treat or prevent disease."

Rival chicken producer Perdue Farms announced last summer that it had stopped using all antibiotics in its hatcheries, including gentamicin, because it wanted "to move away from conventional antibiotic use" due to "growing consumer concern and our own questions about the practice."

Gentamicin has been commonly used in hatcheries to fight off infection or prevent disease, including in fertilized eggs, livestock veterinarians and other poultry producers say.

Tyson sees the policy shift as "a significant first step toward our goal of reducing the use of antibiotics that are also used in human medicine," according to its website.

Tyson has reduced the volume of medically-important antibiotics used in its chicken business by 84 percent since 2011 and the "vast majority of the antibiotics used to raise our chickens are never used in humans," according to a company statement.

While veterinary use of antibiotics is legal, the risk is that overuse could spur the creation of so-called superbugs that develop cross-resistance to antibiotics used to treat humans. Reuters found last year that major U.S. poultry firms were administering antibiotics to their flocks on the farm far more pervasively than regulators realized.