It is not often that environmental groups praise McDonald’s. So when they do, it is probably with good reason. Such is the case with the company’s announcement, cheered and engineered by Environmental Defense, last week that it was asking meat suppliers, mostly of chicken, to reduce their dependence on growth-enhancing antibiotics. The reason this is good news is that McDonald’s is such a huge corporation that its actions have massive effects elsewhere.

McDonald’s is the world’s largest restaurant chain and one of the largest buyers of meat. Last year, the company bought 2.5 billion pounds of beef, poultry and pork. When a supplier needs to change their practices for a company that big, they tend to change them for all their customers.

The problem is that farmers are increasingly giving antibiotics to healthy animals to promote growth and stave off disease. Because they are exposed to the drugs, these animals, and ultimately humans, will develop bacteria that are resistant to antibiotics, a potential health crisis. The nontherapeutic use of these drugs in livestock has increased 50 percent since 1985, according to the Union of Concerned Scientists. The group estimates that more than 24 million pounds of antibiotics, many of them the same or similar to drugs used to treat humans, are fed to cows, pigs and poultry each year.

The change will mean less antibiotic use and perhaps more importantly that the animals’ short lives will be better. Antibiotics are often used to combat cramped, dirty conditions at some farms. Less drug use could mean better living conditions for cows, pigs and chickens. McDonald’s also led the charge to change the way animals and kept and slaughtered. The chain, along with Burger King and KFC, hired animal-welfare specialists and developed new standards for the humane treatment of animals. Because of the weight of these companies, large meat producers and farmers redesigned stalls and slaughtering systems. Other fast food chains have already said they are contemplating following McDonald’s on the antibiotic issue.

While some major meat producers support the antibiotics reduction, meat industry groups say it is unwarranted. There is, in fact, some dispute over the science of the antibiotics’ effects on humans. But given the increasing public awareness of the living and slaughterhouse conditions for animals rendered into fast-food products, the decision by McDonald’s was an important sign of progress.