Fast-food industry leader McDonald’s (MCD) on Monday said it had completed its shift to only using chickens raised without antibiotics important to human medicine, months ahead of its estimated March 2017 target.

Concern has been growing among public health experts, consumers and shareholders that the overuse of such drugs is contributing to rising numbers of life-threatening human infections from antibiotic-resistant bacteria dubbed “superbugs.”

An estimated 70% of antibiotics important to human health are sold for use in meat and dairy production.

Veterinary use of antibiotics is legal. However, as the number of human infections from antibiotic-resistant bacteria increases, consumer advocates and public health experts have become more critical of the practice of routinely feeding antibiotics to chickens, cattle and pigs.

Wendy’s and its chicken suppliers have been working to eliminate all antibiotics important to human medicine from chicken production, the company told Reuters on Thursday. As of June 2016, half of Wendy’s chicken supply was raised without medically important antibiotics. Wendy’s said it would be at 100% by next year.

Wendy’s, which purchases more than 250 million pounds of chicken annually, also said it would commit to specific goals for the reduction of antibiotics important to humans in pork and beef production in 2017.

With regard to beef, Wendy’s said it is engaged with academics and industry experts on work that includes trials for probiotics, vaccines, feed supplements and nutrition composition.

The company posted the new policies to its website on July 28, but did not otherwise publicize the change, before speaking with Reuters.