Tests on the remains of deer belonging to property developer Mr Phil Monahan found evidence of starvation and neglect.
The tests were carried out at the Department of Agriculture laboratories in Abbotstown, Dublin, on carcasses taken from the red deer farm at Glyde Farm, Tallanstown, Ardee, Co Louth.
A Garda investigation into the deaths is continuing and has ruled out poisoning as the cause. At the time it was suggested by a spokesperson for Mr Monahan that they could have been poisoned.
A spokesman for the Department confirmed the tests had found evidence of starvation. "It was neglect and starvation. There was a parasite present in the airways but this was a smaller factor. They also had a copper deficiency as a result of starvation."
More than 50 deer died over a number of days at Christmas and the New Year. They were part of a herd of 400 being farmed on 20 acres of land including woodland, their natural habitat.
At the time of the deaths a spokesperson for Mr Monahan told RTE "the possible explanation is there has been some substance introduced into the feeding. There are some natural substances that will kill them but none of these are present on the deer farm." He said it appeared the animals had been poisoned but the outcome of the tests were still awaited. The river Glyde, which borders the southern end of the farm, was flooding over Christmas and it was suggested a pollutant could have been in the water.
The ISPCA also began an investigation but the findings are not yet known. ISPCA inspector Mr Sean Mellon said a complaint was received by him and within an hour the deer farm had been inspected. "There were animals lying dead when I got there," he said.
Gardai in Louth village are investigating the matter and Supt Michael Staunton, Dundalk, said: "I want to allay public fears about them being poisoned. It would be a matter of concern if they had been but tests on the carcasses found no traces of poison."
A spokesperson for Mr Monahan said yesterday that tests, also carried out at Abbotstown, for Mr Monahan, had been inconclusive as to the cause of death but had found stomach fluke and chicken fat around the animals' hearts. When told that the Department of Agriculture said the deer had suffered neglect and starvation he said: "That is news to me."
"These animals died in the beginning of January. This is February 16th and if the animals were dying of neglect and starvation it doesn't take upwards of a month and a half to find that out. At the time the Glyde river was in full flood and water from it was on the farm. The Department of Agriculture did not take samples of the water or food, only a carcass. If they were dying of neglect they would all be dead," he said.