In a statement, the department said that ABP Food Group, who operate the plant, had indicated that none of the meat had entered the food chain.
The investigation is focusing on the full supply chain including the meat trader concerned and others who facilitated the purchase of the product and its transfer to users in Ireland.
Traces of horsemeat were found in processor Silvercrest, also managed by the ABP Group.
DNA was also discovered in food suppliers Liffey Meats and Dalepack Hambleton.
More top news
UKIP's biggest donor, the Yorkshire multi-millionaire Paul Sykes, has told ITV Calendar he's not planning further donations to the party.
Consumer groups say the presence of campylobacter's in so much supermarket chicken should shame Britain's biggest grocery chains.
The UK is one of the most open countries in the world to foreign investors. Is that good for our economy?