Another 1000 cattle on a newly identified infected Waimate property will be culled on top the 4000 cattle already scheduled for destruction because of Mycoplasma bovis.
The latest farm to test positive is one of two in the Waimate district placed under restrictions last week.
Testing was ongoing on the second property, while a further farm in the area was yesterday placed under the same controls while further testing was done to determine if it was infected.
All three farms were in the same district and several neighboured Van Leeuwen Dairy Group properties, the Ministry for Primary Industries' response incident controller David Yard said.
The culling of about 4000 dairy cattle from five Van Leeuwen Dairy Group properties has been signalled following an outbreak of the bacterial disease which could cause mastitis, abortion, pneumonia and arthritis.