National Beef Packing Co., the fourth-largest beef processor in the country, is laying off 283 workers at its plant in Moultrie, the company said Wednesday.

The Kansas City, Mo.-based company, which last fall lost Wal-Mart as a major customer of meats packaged at the southwest Georgia plant, said in a statement that the layoffs are connected to the loss of a major customer, though it did not mention Wal-Mart by name.

The company said it is also laying off 150 workers at a plant in Hummel’s Wharf, Pa.

“National Beef was notified in October by one of its key customers that it would transition away from using National Beef as a supplier of case-ready beef,” the company said in a statement sent to The Atlanta Journal-Constitution. “Today, there are no plans to close the Hummel’s Wharf or Moultrie facilities; however, they will begin to operate at reduced levels.” Case-ready means meat that is processed and packaged at a central facility and delivered to the store ready to be put directly into its meat case.

The company said it is working to bring additional business to each facility and to preserve remaining jobs. The layoffs were first reported by Meatingplace.com, a trade news site.

The southwest Georgia plant, one of the largest private employers in Colquitt County, has been in operation since 2001. It produced case-ready hamburger, beef and pork products for Wal-Mart, according to The Moultrie Observer.

The newspaper said National Beef received a $1.5 million grant from the state’s OneGeorgia economic incentive program when it opened. Before the layoff announcement, employment had grown to more than 450 workers from about 120 when the plant opened.

The 433 layoffs at both plants become effective April 13, the company said.