A long simmering dispute has escalated at five AFFCO meat works where 760 union members have been warned they will be locked out from Wednesday.
The plants are at Moerewa, Horotiu, Imlay, Wairoa and Manawatu.
AFFCO is offering a pay rise of 4.3% over two years if a collective agreement is reached with the Meat Workers Union without dispute.
But the company will lock out those who do not sign, saying continuing contractual challenges are threatening its ability to manage its plants.
The union says AFFCO is trying to starve its members into accepting major changes to their collective employment agreement by giving the company total flexibility in their terms of employment.