Federated Farmers says many calves bought for Northland farms from the Waikato originated in Southland, raising fears about Mycoplasma bovis.
Northland Federated Farmers president John Blackwell said there was a lot of concern among beef farmers in the region because it was understood many of the hundreds of 100kg calves they bought annually from the Waikato were not born there, but were brought up from Southland.
"Some of these calves spent only about four days in the Waikato," Mr Blackwell said.
Northland farmers buy in the calves to avoid the tick-borne theileria blood parasites which can be fatal for young cattle in the North.
He said it had not been made clear to the calf buyers that some of the animals originated in Southland.
Blackwell attended two meetings which the Ministry for Primary Industries (MPI) and DairyNZ held in Northland on Monday to give farmers an update on the M. bovis response.
About 350 farmers attended one of the meetings at the ASB Leisure Centre in Whangarei and about 260 were at the other meeting in the Turner Centre at Kerikeri.
Speakers at the meetings were MPI incident controller Dave Yard, MPI veterinarian John O'Connell, Beef + Lamb GM policy and advocacy Dave Harrison, and the Rural Support Trust's Julie Jonker.
Dairy NZ senior communications and media specialist Vanessa Feaver said there was a good mix of dairy and sheep/beef farmers at both events, along with a number of rural professionals.
"The meetings were positive and focused on how farmers could get a better understanding of M. bovis, including how to protect themselves from M. bovis," she said.
"There were a number of questions around NAIT, risks for farms and managing mating and service bulls."
Asked about calves being purchased from other regions, Feaver said DairyNZ recommended farmers buying calves question the seller about the source and health of the animals they are buying before confirming any purchase, so they are confident they have the information they need to assess any risk to the farm business.
"Animals must have a NAIT tag when they leave the property of origin or by six months of age, and National Animal Identification and Tracing (NAIT) scheme records completed."
A map dated May 30 on the MPI website shows two Northland farms are under MPI notices of direction restricting cattle movements.
Blackwell said Northland Federated Farmers had two proposals for presentation at the federation's national conference in Wellington next week.
The first was for an independent inquiry into Biosecurity NZ and the other for an overhaul of NAIT, which he said no longer appeared to be fit for purpose.
"It seems outdated. When I buy cattle today I find out only the name of the person selling the animals. There may be no farm of birth. More information is needed," Blackwell said.
"The Government has been sleeping in biosecurity for the past six years. No farmers have been prosecuted for NAIT infringements and some may have to be taken to court to make them comply."