A Southland farmer is concerned the Mycoplasma bovis disease could be back on his farm, 18 months after his previous cattle herd had to be culled.
The disease can cause mastitis, pneumonia, arthritis, and late-term abortions.
Ben Walling and Sarah Flintoft had 1700 cattle culled after M bovis was discovered on their farm which was later declared disease-free.
Afterwards, they told RNZ they hoped they would never have to go through such an ordeal again.
But now the Ministry of Primary Industries is back on their farm, and hundreds of cattle are having to be blood tested for the disease.
Walling said some of the animals under suspicion are replacements for the cattle which had to be culled originally. They are Friesian bulls born in 2016 and bought last year.
"We ended up with a lot of feed left over that we needed to be eaten ... rather than putting a claim in for the feed and ploughing it under and wasting it we went out and bought bulls and restocked ourselves and [they] ate the leftover feed on that property," he told Summer Report.
He said $300,000 worth of feed would have had to be ploughed under if the couple had not re-stocked.
"These animals turned out to have trace animals in them from another infected property that has recently been found."
Trace animals are those which have had some contact somewhere along the line with an infected animal.
Two hundred and fifty cattle have had their blood tested and the final results are due in the next few weeks.
He was hopeful the results would come back clear.
"If the blood testing is more than 3 percent antibody infections we will immediately go into an infected property."
As of late December, there were 23 active properties with M bovis - all of which are under quarantine.
A lot of resources have gone into animal tracking since the outbreak - and the system that does the tracking work, the National Animal Identification and Tracing programme, or NAIT.
Legislation rushed through in 2018 strengthened the Ministry of Primary Industry's search powers under NAIT, requiring all animal movements to be registered within the system and ensured farmers who flouted the rules would be held to account.
This came as the government decided to attempt to eradicate the disease, rather than adopt farming practices that could live with it.
Walling said, in his experience, many farmers are not properly registering their animal movements.
He's running 2700 bulls bought and traded over the last couple of years and NAIT was coming back to him on a weekly basis about cattle having the incorrect number or cattle that should be in their name listed with another farmer because of incorrect transfers.
MPI's director of response Geoff Gwynne told Summer Report he sympathised with the couple but MPI had been involved with over 1400 properties and there were fewer than 20 farms that had to be revisited.
He agreed that NAIT was "not as good as it could be", however, it was being improved by a variety of people.
The database was owned by not-for-profit OSPREY, that consisted of farming organisations such as Beef + Lamb and Dairy NZ. "So it's a farmer problem being resolved by farmer organisations."
He said farmers on the ground could drive compliance by not accepting animals on their property they had any concerns about or not buying cattle that were not NAIT-compliant.
He was confident MPI was doing as much as it could to enforce the NAIT regulations.
It had carried out 2400 on-farm checks in the last 12 months, issued 200 notices of direction and 691 infringements. It had taken one prosecution and he anticipated there would be more especially as a result of a targeted campaign due to get underway this month.