The union said it was left with no choice but to take industrial action because the company had consistently breached labour relations procedures with new work practices.
Dairygold denies it has broken agreements and has accused SIPTU of embarking on an “unwarranted, provocative, and wholly irresponsible” strike.
All of the Dairygold depots, mostly in Munster, will be hit by the action, which follows 500 redundancies implemented before Christmas.
Further job losses are expected as the co-op restructures its loss-making milk processing operation at the two Mitchelstown, Mallow and Mogeely sites.
A Dairygold spokesman said that under current circumstances the company is forecast to incur significant mounting losses in the coming years.
He said in an effort to stem these losses, it had incurred its largest one-off cost in the €40 million severance package made available to staff leaving the business in the recent past.
However, further disruption to the business will make it impossible for the company to fund further severance packages of this nature.
“We are hopeful that a Labour Court hearing scheduled for Thursday next will provide us with a recommendation, which both parties can embrace as a positive solution to outstanding rationalisation issues needing resolution,” the spokesman said.
SIPTU Mitchelstown branch secretary Anne Egar said all the union is seeking from the company is a commitment that it would abide by the agreement reached with it in good faith.
“Dairygold’s consistent breaches of our industrial relations procedural agreement have left us with no alternative but to take industrial action.
“We acknowledge that the company is in financial difficulty and indicated our willingness to negotiate change and to do so within an agreed time frame if necessary,” she said.
Ms Egar said in line with best industrial relations practice, SIPTU remains available for negotiation at all times.
Proposed industrial action by SIPTU members at the co-op’s pig farms in north Cork and Tipperary, which was to start yesterday, was put on hold pending a meeting between the company and the union.