About 200 cows on farms in the Hokitika Valley died from hypothermia when temperatures suddenly plunged to below zero last week.
Kokatahi dairy farmer, Barry Paterson, a supplier and director of the Westland Milk Products co-operative, was the worst hit, losing 180 cows, almost half of his herd.
Chief executive Rod Quin says the conditions that killed the cows were unlike anything local farmers had experienced before.
He says it was a very isolated case of a weather bomb and it wasn't rain or sleet, but frozen ice going sideways.
"It happened so quickly that these animals, and the herd was on the move, it literally stopped them in their tracks and the ones that stopped couldn't be encouraged to move again and the situation escalated from there. And a number of the stock remained where they were and subsequently died".
The Ministry for Primary Industries is investigating the deaths, to check whether there was any breach of animal welfare laws.
But Mr Quin says the cows in Mr Paterson's herd were in top condition and even vets who were called out to help rescue the cows couldn't save them.
He says they were healthy animals and at an average price of just over $2000 per animal, it would mean a significant loss of around $300,000 - $350,000 which would have a major impact on any farmer.
Community and farming representatives in the valley are meeting on Thursday afternoon to discuss how they can support the farmers.