Some 1,500 farmers have protested outside the headquarters of Glanbia in Kilkenny over the move by the company to cut the price they pay farmers for milk by 4c per gallon.
The IFA leader, John Dillon, urged dairy co-ops to stop cutting milk prices to farmers, warning there would be no future for the industry if they continued.
At the demonstration, Mr Dillion said the price cut would cost a 60,000 gallon dairy farmer €2,400 or 12% of his income.
He said that over the past four years the group had reduced prices by 18c, slashing dairy farmers' incomes by 40%.
Mr Dillon claimed that farmers were being used to subsidise the share price, saying that following the recent price cut, the Glanbia share price was boosted by 7c.
He warned Glanbia and other co-ops that without viable dairy farmers, there will be no dairy industry.
He also called on processors to improve efficiency by cutting administration and management.
The Fine Gael spokesman on Agriculture, Denis Naughten, has also reacted angrily to the price cut.
Mr Naughten said it is now clearly evident from the dramatic cut in lamb and milk prices that the major food companies are trying to get their hands on the new single farm payment which farmers will get later in the year.
