Cargill has resumed normal operations at a large beef processing plant in Schuyler, Neb., after a number of employees walked out Tuesday over a negotiated pay-shift differential.

The employees were working the first shift at the slaughterhouse and upset over a new pay raise given to second- and third-shift workers. The company said it had negotiated that pay differential with the labor union, United Food and Commercial Workers (UFCW), as a way of attracting workers to the later shifts.

The situation highlights ongoing challenges large meatpackers face in staffing slaughter and processing positions across the U.S.

Cargill spokesman Mike Martin said the company implemented the pay difference on a six-month trial basis in hopes of enticing workers at a time when the area has low unemployment and increased competition for labor. These conditions, as well as an improving economy, have led more employees to seek first-shift positions, often considered more desirable.

“Across the U.S., over 750 jobs at our plants remain open and unfilled every day,” Martin said. He said the company is giving them the chance to bid on second- and third-shift positions based on seniority. The company said it continues to honor all of the terms of its labor agreement ratified in 2015 by the UFCW and its represented employees.

The work stoppage occurred during Tuesday’s first shift, but operations returned to normal by second shift. Wednesday’s first shift occurred as usual.

The Schuyler plant processes more than 5,000 head of cattle a day and employs more than 2,200 workers.