The death of 120 cows on a South Taranaki farm on Tuesday is believed to have been an isolated incident.
A Ministry of Primary Industries spokesman said the investigation into the cause of death was still in early days and could not give a timeframe for its completion.
He said the ministry is confident the deaths of the cattle were an isolated incident.
Vets rushed to the Oeo farm of Chris and Catherine Cook this week but could not save the dying animals, part of a herd of 600 and worth hundreds of thousands of dollars.
Yesterday, vets were not saying what caused the deaths but did rule out nitrate poisoning as a cause.
Meanwhile, Whakatane dairy farmer Rod McPherson has launched an appeal to farmers across the country to pitch in a cow apiece to help the Cooks, Taranaki's sharemilkers of the year in 2007, replenish their herd.
Mr McPherson was inspired by the generosity from the farming community he had received in the past.
"It's just what we do, there must be 12,000 cows in the area so surely we can muster up 120."
DairyNZ Taranaki regional leader Katrina Knowles said she would be co-ordinating the donation effort with Fonterra, Federated Farmers and Road Transport New Zealand.
She said people with an animal to offer could ring the Fonterra 0800 number and their details would be passed on to her to arrange transport.
Offers were already rolling in yesterday afternoon, from as far afield as the Bay of Plenty and Waikato.
"The farming community are good at helping others in the community, it will likely spread through word of mouth," Mrs Knowles said.
Mrs Cook's brother John Murphy said the couple were not ready to speak about the ordeal but were grateful for the support they had received.
He said the Cooks were overwhelmed by Mr McPherson's gesture. "What a brilliant guy. I've just been on the phone to him giving him a pat on the back."
Neighbours of the Cooks are also standing behind the family, with offers of meals, cows and help on the farm.
Oeo farming contractors Andy and Bev Davy said they had not heard details of what had happened to the cows and did not want to make assumptions.
Mrs Davy said it was bad enough to lose one or two cows, let alone 120.
"It's not just the financial side but the emotional and psychological effect."
They did not have cows to give but would support the Cooks by helping with farm work, she said.
"It's human nature to help anybody in strife, regardless of whether they have insurance."
About 20 cows were still sick.
A spokesman for the Ministry for Primary Industries has said the ministry is working closely with the family, vets and Federated Farmers but has declined to comment on the incident because it is under investigation.
It was too early to know how long the investigation will take, he said.
Industry leaders said the farmers would be unlikely to be insured against such an event.
Federated Farmers Taranaki president Harvey Leach said most farmers didn't insure their herds because it was too expensive.
"Cows die, that happens every year and you just can't afford it (insurance).
"It's just one of those ones where you just have to take the loss."
- Taranaki Daily News
Testing drugs on animals is:Related story: Animal tests 'key' to brain disease cures