Roughly 3,800 employees at a major beef processing plant in Greeley, Colorado, began a strike early Monday morning after contract negotiations between the workers’ union and plant owner JBS USA failed to produce a new labor agreement.

The walkout started at 5:30 a.m. local time at the Swift Beef Co. facility, one of the largest beef processing plants in the United States. The workers are represented by United Food and Commercial Workers Local 7, whose leadership said the strike was authorized after negotiations stalled ahead of the expiration of the previous labor contract at midnight Sunday.

Union officials accuse the company of retaliating against workers and engaging in unfair labor practices during negotiations. According to union representatives, employees were called into one-on-one meetings where management allegedly attempted to pressure workers to leave the union.

Kim Cordova, president of UFCW Local 7, said union members overwhelmingly supported the strike authorization, with 99 percent of participating workers voting in favor of a walkout. Union general counsel Matt Shechter said no formal bargaining sessions occurred over the weekend after the company declined a request to resume negotiations Saturday.

JBS USA disputed the union’s claims and said the company intends to continue operating the facility. In a statement, the company said any employees who choose not to participate in the strike would be allowed to work and receive pay. The company also said it plans to run two shifts at the plant on Monday and may temporarily shift production to other facilities within its network if necessary.

“Our goal is to minimize impact to our customers, our partners, and the broader marketplace while we work toward a fair resolution in Greeley,” the company said in a statement, adding that it operates in compliance with federal and state labor laws.

The labor dispute comes at a time when the U.S. cattle supply is already historically tight. According to federal data, the U.S. cattle inventory stood at about 86.2 million animals as of Jan. 1, the lowest level in roughly 75 years and about 1 percent lower than the previous year.

Tight supplies have contributed to rising beef prices, adding pressure to food costs nationwide. The administration of President Donald Trump has sought to address some of those pressures through international trade agreements, including a deal with Argentina aimed in part at increasing beef supply.

The strike also follows the closure earlier this year of a meatpacking plant in Lexington, Nebraska, a shutdown that local officials warned could have broader economic consequences for the surrounding community.

Union leaders say the Greeley strike could become a major labor dispute within the meatpacking industry. According to Cordova, the last comparable strike at a U.S. slaughterhouse occurred in 1985 at a Hormel plant in Minnesota, a labor conflict that lasted more than a year and included clashes between police and protesters.