The Meat Workers Union says it is a lie to say production at AFFCO plants has not been affected by strike action.
About 700 members of the union who avoided being locked out of the plants began a 48-hour strike on Monday morning in support of 1000 colleagues locked out by management on 29 February.
The affected plants are in Moerewa, Horotiu, Rangiuru, Wairoa, Feilding and Whanganui.
AFFCO and the union are at loggerheads over flexible hiring practices.
Management says similar strikes before have not halted production and it will stand firm.
It says proper disputes procedures must be followed, there needs to be proper drug testing and management must be able to manage their factories.
A spokesperson for the union, Graham Cooke, says the company's claim about production not being affected is "rubbish".
Mr Cooke says workers who are on individual contracts, and therefore not caught up in the strikes, are usually newer employees with less experience.
He says he would feel nervous about sending his meat there to be butchered while the strikes are on.
Workers at AFFCO plants in Wiri and Napier, which are not affected by the lockout, will strike for two days from Wednesday.