Up to 400 jobs could be under threat at Moy Park in Ballymena, after the company confirmed plans to temporarily halt one of its production lines.
The company has said there will be no job losses and that the move is only temporary.
However, the union Unite says there are fears among staff that the closure of the company’s kill-line and hatchery will be permanent.
The move by Moy Park will also have implications for farmers who supply the company.
A spokesperson said: “Moy Park is proposing to temporarily cease processing live birds at Ballymena due to challenging market conditions, with the view that we will re-open the line in January 2020.
“In line with this, it is proposed the North Antrim Hatchery will temporarily cease hatching until November 2019.”
The spokesperson added: “We are currently working with our colleagues and their representatives doing our utmost to minimise the impact of this proposal on our excellent workforce, including offering temporary transfers to other shifts and roles.
“We will also be working closely with our farming partners throughout the process to manage this temporary reduction in poultry requirement.”
Unite Regional Officer Sean McKeever said: “The workforce have been left with little confidence that the promised investment will manifest or that the line will reopen as promised in January 2020.
“If they are genuine about these promises, Moy Park management must offer guarantees that no worker, whether agency or otherwise, will be made redundant.”
He added: “In the absence of such a commitment, this decision effectively threatens to sacrifice the livelihoods of up to 400 workers and 400 families in Ballymena for corporate greed and the drive for ever greater profits.”