The Meat Workers Union says it will go on strike for five days after mediation talks with AFFCO ended on Thursday with no progress being made.
The meat processing company and union have been in a dispute over a new employment agreement for six weeks, with 800 union members shut out by AFFCO and 500 on rolling strikes.
The union's national secretary, Dave Eastlake, says the parties only had one face-to-face meeting all day on Thursday.
Mr Eastlake says workers will now go on strike from 5am on Friday.
It is the longest strike action by workers to date.
The dispute has become increasingly bitter. AFFCO operations manager Rowan Ogg says the company has critical commercial reasons for updating the collective employment agreement, because times are tough in the meat industry.
Mr Ogg says AFFCO stands by its proposed changes in order to preserve jobs in the long-term.
The Meat Workers Union says the proposed changes would strip its members of job security.
Meanwhile, a locked-out worker brought to the mediation was told that his presence was making the company uncomfortable, so he left.
Laurie Nankivell says he travelled from the town of Moerewa with five of his children to meet AFFCO management on Thursday.
"I suppose we were trying to put a face to what they're doing, rather than just figures and numbers ... these are actually real people, real kids and that's what we're trying to show."