The two main farm organisations have targeted co-operative workers' pay levels in their dispute with the co-ops, which have cut the milk price they are paying to farmers.
Jackie Cahill, president of the Irish Creamery Milk Suppliers' Association, criticised the creameries for taking "the unjust" option of cutting the price to farmers instead of trying to balance their books out of their own resources.
"In the case of Glanbia, co-op employees who are on substantially more money than their farmer counterparts will receive another pay rise shortly, while the farmer suppliers - who actually own the co-op itself - will see their price cut and their incomes fall by up to 16 per cent per annum," Mr Cahill said.
"In the case of Lakelands, the cut will mean that the farmer suppliers will see their incomes cut by up to 19 per cent per annum. It is outrageously unfair and unjust, and the income situation for many farmers is becoming unbearable," he said.
"The average dairy farmer is earning half the income of a worker in a co-op, and that is not sustainable," Mr Cahill said.
IFA president Pádraig Walshe also highlighted the difference between dairy farm income and the workers in the co-ops.
"The average farmer with a 50-cow herd is earning only two-thirds of the average industrial wage. Over the last five years, farmers have already lost €9,000 in annual income due to steep price cuts," he said.
"Production costs are rising and eating further into farmers' margins," he said.
Both organisations plan protests over the six cent per gallon cut announced by Glanbia, the country's largest processor of milk, and Lakeland Dairies in Cavan, last week.
Dairy farmers have been coming under increasing pressure in the past two years because of falling demand for product, increased competition from abroad and reduced EU market supports.