Eight calves were killed after they succumbed to slurry fumes in Co Kerry on Monday, according to vet Richard Hurley.
The pen of young calves, being bucket reared, died on a farm outside Tralee.
The farmer was agitating slurry in a "big shed" and moved the calves to a pen further away, but which “wasn’t far enough”, said Hurley.
All animals in the pen succumbed to the slurry fumes.
“You shouldn’t have any life - human or animal - near slurry when it is being mixed. If the calves are going to go down, you’d go down,” he said.
The animals have been removed to a knackery and the Department of Agriculture has been notified.
“You could see how it could easily happen,” warned the Kerry vet.