A 24-hour strike at Dairygold businesses went ahead yesterday affecting its meat and dairy processing plants and 39 retail outlets.
The action was taken by approximately 1,700 SIPTU members out of the 2,500 workforce in spite of a scheduled meeting in the Labour Court to be attended by management and union representatives tomorrow.
Ms Anne Egar, of SIPTU, said there had been persistent and consistent breaches of agreement by the company.
"Very reluctantly, we found that the company gave us no other choice," she said.
Ms Egar said staff were prepared to make changes but they would have to be consulted about the implementation of change.
The company got two weeks' notice of industrial action and was aware of it last Monday, she said.
The reason the action went ahead in spite of the upcoming Labour Court hearing was that the company had taken provocative action, for example, they had re-employed people laid off previously who were not the most senior staff, Ms Egar said.
"The union was pushed by the company. We did say we were available to talk," she said.
The union would be waiting to see what the company had to say at the Labour Court hearing, she added.
A Dairygold spokesman said the company had been going through a difficult time since 2002 and losses had continued. The company needed to cut costs and a rationalisation programme was introduced last autumn after negotiations between SIPTU and management under an internal council.
It was agreed last October that there should be a severance package with the loss of 500 jobs, and 498 were achieved on a voluntary basis.
"We think the industrial action is unjustified. It is certainly odd. Having said that, we are looking forward to going to the Labour Court this Thursday and dealing with the issues," the spokesman said.