The blooded remains of the one year old calves were found half-eaten on the farm outside Convoy, near Raphoe, yesterday morning.
The one year old animals, which would have been a considerable size, had a number of their ribs broken.
The family at the centre of the attack and animal welfare officers are baffled as to who or what killed the animals.
The attack will again raise suspicions that a large wild cat is still roaming the north-west after sighting in recent years.
Nicola Gregg, whose husband found the dead animals, said it was a very upsetting experience to think about what the calves went through before they died.
She said she simply didn’t know what had attacked but suspected it may have ben a larger animal.
“I know there have been escaped wild big cats like pumas before here and in other countries and I’m convinced something like that has happened here.
“If this is the case, it is only a matter of time before this animal or animals do this again and farmers should be mindful of that.”
She said they would be taking steps to protect other livestock on their farm.
“My husband heard the calves roaring and when he went down to count them two were missing. When he investigated he saw they had basically been eaten alive.
“Their heads were fine it was just the stomach area, and the back and tail. They demolished more or less.
“Their ribs were broken which made us think it must have been something really strong to have done that.
“My husband said he had never seen anything like that in his life. It’s sad and it is worrying.”
Mr Gregg had the animals removed and disposed of.
Local RSPCA inspector Kevin McGinley said he found it hard to believe that a dog or dogs would have been able to inflict such damage on such animals.
However he said because the animals had been disposed of, there was no definite way of identifying what had happened to them.
“We were not officially informed about the matter but I would find it difficult to accept that dogs were able to do this.
“These animals were a year old and they would be a considerable size so it would take a lot to take both of them down,” he said.Tags: