Cattle culling is continuing on the South Canterbury dairy farms infected with Mycoplasma bovis.
All cows have been removed for slaughter from the first two farms in the Ministry for Primary Industries' ''depopulation'' programme.
The number of farms where the bacterial infection has been confirmed since July remains eight, and 21 properties are still under quarantine restrictions.
After all the infected herds are culled, the farms will be disinfected and go into a stand-down period when no cattle will be allowed there.
The ministry has quashed what it said were ''stories circulating in the farming community that M. bovis survives in soil for years''.
That was only the case with Mycobacterium bovis, the organism that causes bovine tuberculosis, it said in its latest update on Thursday.
''Mycoplasma bovis does not survive in soil for a long period. The stand-down period is long enough to ensure that cattle are not infected from the soil.''
Silage would not spread the disease if it was ''properly made'' with a pH of 4 or below and wrapped correctly, the ministry said.
It also reminded the public that there is no food safety risk for humans - ''it is a disease that affects animal welfare and production''.
''It is common in many food-producing nations (like Australia, the United States, and in Europe). In these nations, infected animals that aren't showing symptoms are processed for human consumption.
''Most cattle that we're culling as part of the depopulation operation will be processed. Before they leave the farm, the animals will be assessed by veterinarians to confirm that they're suitable for transport.
''At the processing plants, MPI veterinarians will assess the health of each animal before they get slaughtered. Animals will not be killed for human consumption if they are sick, or are severely injured, or have medicine in their system.
''This is a requirement of New Zealand law. All animals must also be examined after they're slaughtered. This is to ensure the meat is safe and suitable for consumption.''
The slaughter was taking place at Oamaru Meats and Anzco, which had special programmes to meet ministry regulations. The trucks used would be disinfected under ministry supervision after each trip.
Ministry response incident controller David Yard told the recent public meeting at Morven that farmers should take their own on-farm measures to reduce the risk of infection, and keep accurate animal movement records.
Oamaru vet Mat O'Sullivan said ''a lot of farmers have got very lax with their disinfection points''.
They should make sure contractors could easily disinfect themselves and their equipment when they arrived and before they left the farm, he said.
A farmer in the audience said all farmers needed to take ownership of biosecurity.
''We beat brucellosis. We beat hydatids. We can do this.''