Fonterra subsidiary Canpac will axe 30 jobs at its Hamilton canning factory, sending the jobs overseas.
In a statement the company said it would be outsourcing its press and print operations to save costs.
"With reduced demand in these parts of the business and taking into account the cost efficiencies of outsourcing - particularly at a time of low milk price - it is important we consider all alternatives that will drive cash back to our farmers," Fonterra's New Zealand manufacturing director Mark Leslie said.
Union E tu, which represents 21 of the affected staff, said the workers were highly skilled metal decorators and press setters, and options to take other roles at the company would not use that training.
"There's a feeling of great sadness. These workers have worked together for a long time, and they've worked really hard. They've won awards including a Supreme Award for packaging at the Pride in Print Awards," union advocate Fiona McQueen said.
Fonterra also cut 110 jobs at the packaging plant in 2014.