A group of 350 to 400 farmers protested outside the Greencore's AGM in the Berkley Court Hotel in Dublin this morning.
The farmers were protesting at the closure of the Carlow sugar plant and the Banagher, Co Offaly, malting plants earlier this year.
At the protest the Irish Farmers' Association (IFA) President, Mr John Dillon, said the decision to close the plants was "premature before the outcome of EU negotiations is know at the end of this year.
"There is no justification for Greencore's decision to shut a profitable plant and then try and impose costs on beet growers," Mr Dillon said.
He demanded the closure be "deferred for one year to allow an orderly negotiated plan be rolled out to get the beet to the Mallow factory at no additional cost to growers.
"Greencore has failed to honour an agreement between IFA and Guinness whereby traditional malting barley growers were assured of a secure market for their product into the future," he sajd.
Some of the farmers have continued to Leinster House to lobby their local politicians about the closures.