NEW YORK — Wal-Mart, the nation’s largest food retailer, is urging its thousands of U.S. suppliers to curb the use of antibiotics in farm animals and improve treatment of them.

That means asking meat producers, eggs suppliers and others to use antibiotics only for disease prevention or treatment, not to fatten their animals, a common industry practice. Experts say Wal-Mart is the first major retailer to take a stance to limit the use of the antibiotics.

The guidelines also aim to get suppliers to stop using sow gestation crates and other housing that doesn’t give animals enough space. They’re also being asked to avoid painful procedures like de-horning or castration without proper pain management.

The push is part of an industry trend responding to shoppers who want to know more about where their food comes from and who are choosing foods they see as more healthy or natural.