Bernard Matthews has laid off 33 extra staff in the wake of the avian influenza (AI) outbreak that has led to a drop in sales of 40%.
This is in addition to the 130 jobs that were lost last week.
In a statement, the company said: "Given the recent drop in product sales this was the only option available to Bernard Matthews.
"Talks between Bernard Matthews and the Transport and General Workers Union (TGWU) remain ongoing and the TGWU has agreed to the layoff proposal.
"Bernard Matthews continues to communicate with its staff regularly and is doing everything possible to restore consumer confidence and limit the number of job losses."
Matthew Pullen, marketing director for Bernard Matthews, said the company hoped to reinstate the workers if sales recovered. He told MTJ: "A further 33 production staff were laid off. It is not a redundancy and we're hoping as sales recover we'll be able to bring those people back into the business. It's unfortunate but we did announce at the time there could be up to 500. We're hoping that's not going to be the case but we obviously have to allign our cost base to our sales so that's the reason for it."