Receivers Michael Stiassny and Brendon Gibson were getting mud on their gumboots yesterday as they came to grips with problems of Crafar Farms, the nation's biggest group of family-owned dairy farms.

Westpac Bank called in the receivers for four of the Crafar companies, Plateau Farms Ltd, Hillside Farms Ltd, Tararua Farms Ltd and Ferryview Farms Ltd, which cover at least 20 of the family's 22 farms.

"It is the bulk of the Crafar interests," said Mr Stiassny, of KordaMentha, who yesterday met the western Bay of Plenty-based farmer at the centre of the family's companies, Allan Crafar.

The Crafar family companies based in Reporoa, 42km southeast of Rotorua, has grown its original property to 22 farms with 20,000 milking cows, 10,000 other stock, 200 staff and a reported $200 million of debt.

Westpac is the security trustee for itself, Rabobank and PGG Wrightson Finance.

The receivers said they are working with the Crafar family and its managers to address financial and operational problems.

"We will be doing our best to ensure it is business as usual for the farms," Mr Stiassny said.

He was unable to give an estimate for the debt levels or the amount of assets available, but sources have said the farms owe about $150 million to the two banks and $25 million to PGG Wrightson.

Mr Stiassny said his initial concerns were to protect animal welfare and the interests of workers.

Mr Gibson told a media conference that many workers on the farms were employed by entities other than the companies in receivership: "There are contract milkers and sharemilkers involved, but we understand there are trade creditors who are unpaid."

He said all staff directly employed by the companies had been paid, but there were unsecured trade creditors.

The Ministry of Agriculture and Forestry has already reported to the receivers on its findings so far, following urgent checks the Government last week ordered on the welfare of livestock at the Crafar farms.

"We will be kept up to date as they move through the rest of the farms," Mr Stiassny said. He noted the current cold snap was raising "pressing issues" around making sure animals received adequate food and shelter.

"We have got snow on the central North Island, which is concerning every farmer out there."

Mr Stiassny said Mr Crafar and he "have common interests around the welfare of the animals on the farms ... and we do have their [Crafar family] co-operation".

"Mr Crafar is of the view that there is not significant expenditure needed to ensure the well-being of the animals and the environment," he said.

The receivers had a lot of advice available from consultants, the ministry and Federated Farmers.

The ministry is expected to announce this week whether it will prosecute over alleged animal neglect after more than 100 calves dying of thirst had to be killed on a Crafar farm.

Mr Crafar claims that he and his family are being unfairly targeted over dirty dairying and animal welfare.