About 100 meat workers at Canterbury Meat Packers' (CMP) Rangitikei plant in Marton are picketing the entrance after the breakdown of negotiations over pay and working conditions.
The picket was set up on Wednesday after CMP issued a lockout notice to members of the New Zealand Meat Workers and Related Trades Union after the collective agreement expired and a new agreement could not be reached.
Plant manager Darryl Mackenzie says the company's financial standing is dependent on meat workers taking a pay cut and working longer hours during the peak season.
Mr Mackenzie says if they work 40 hours instead of the previous 35 hours a week, they would still be able to earn close to their previous pay.
He says the majority of employees have resigned from the union, signed individual contracts and are working.
The union says it would consider changes to wage rates and shift structures, but only if pay cuts are across the board.