Electricians, fitters and boilermakers voted to down tools for 24 hours, affecting maintenance at the busy facility. 

The Electrical Trades Union (ETU) and the Australian Manufacturers Workers Union (AMWU) are pushing for a 4 per cent pay rise each year over three years. 

Both sides have been negotiating since September. 

Up to 50 workers at plants in Cobden, Stanhope and Darnham are taking part while Dennington, which operates under a separate agreement, won’t be included. 

Fonterra said it was “extremely disappointed” both unions had voted to go ahead with industrial action. 

AMWU south-west organiser Mark Solly said the stoppage would disrupt operations. 

“We’ve been in talks with the company this week and while there’s been some progress the issues are still very far apart,” Mr Solly said. 

“In this scenario they can still transfer milk around but it will still be a headache (for Fonterra).

“We are pushing for 4 per cent in wages per year for a three-year agreement ... all we’re asking for is what’s fair and reasonable.” 

Mr Solly said the company was yet to put an offer on the table.

“They’ve been keeping their cards fairly close to their chest,” he said. 

The company says the work stoppage has undermined a pay agreement that it says is within reach. 

“Negotiations between Fonterra Australia and ETU and AMWU have been ongoing since September and 35 of 40 items have been resolved during this process — only five outstanding claims remain and Fonterra has put forward a fair, above-standard offer,” director of operations and ingredients Bruce Donnison said. 

“The company is working through plans to minimise any potential impact on operations. There is no impact to milk collection. 

“Fonterra Australia urges the relevant members to cease their action to ensure there is no impact on other Fonterra Australia employees, farmer suppliers, drivers and customers.”

s.mccomish@fairfaxmedia.com.au