The Meatworkers Union says its members at the Talleys-owned AFFCO meat plant in Wairoa have voted to reject what it calls unlawful lockout tactics.
Meatworkers Union branch organiser Eric Mischefski said union members voted last week to refuse to accept what he described as punitive individual agreements as a precondition to returning to work after the seasonal lay-off.
The vote was part of a long-running dispute to renegotiate a collective agreement which expired in December 2013, with the Employment Court due to hear the dispute in early October.
Mr Mischefski said the contracts introduced significant changes to meatworkers' employment conditions.
"The Wairoa people are saying we've heard what's happened at these other plants and they've said no, we don't want a bar of that and they want the company to honour the current agreement," he said.
"It represents significant changes, for example the requirement to work anywhere over the week - night or day - and potential changes to rest breaks, where at the moment you might have a smoko break in the morning and afternoon with a lunch break in the middle, the company at one plant at least has relegated it down to two breaks per day.
"In some ways you could say the argument is complex but when you talk about having to work 24/7 or anytime within and you are reducing your rest breaks and you are getting a pay cut it's not hard to determine there are significant losses there."
Mr Mischefski said union members will be protesting in Wairoa on Wednesday.
Radio New Zealand sought comment from AFFCO this morning on the dispute but hasn't heard back yet.