A survey of about 200 calf-rearing properties is under way nationwide as the next step in the phased eradication of Mycoplasma bovis.
In a statement yesterday, national controller Geoff Gwyn said the Ministry for Primary Industries started contacting owners of the selected properties this week.
The test involved a one-off nasal swab on calves.
The properties selected were not suspected of having the bacterial cattle disease, rather it was an opportunity to provide further assurances to those farmers, says Gywn.
''The identified properties have no connection to other properties which are being tested or at risk of having M. bovis.