It is checking seven ways it believed the Mycoplasma bovis disease may have got to this country.
“We are looking at imported live cattle, imported frozen semen, imported embryos, imported veterinary medicines and biological products, imported feed, imported used farm equipment and other imported live animals,” MPI said on its website.
“It is possible that we never be able to identify the entry pathway. MPI is tracing movements of possible risk goods onto the affected properties as part of this investigation.”
More than 22,000 dairy cattle will be slaughtered to contain the disease, which until this latest outbreak had never been found in New Zealand.
Farmers say they are worried that MPI is going ahead with the the cull with no knowledge of how the disease got to New Zealand.
This meant it could come into the country again, they said.
MPI said it continued to allow semen and embryos into the country.
“There is no documented scientific evidence from any country showing that Mycoplasma bovis has been transmitted to a cow in semen. Semen is considered a low risk due to a long international history of safe trade and strict hygiene requirements around collection and use,” the ministry said.
“Farmers can continue to make their own decisions around the use of artificial insemination (AI). AI providers have developed biosecurity protocols for use following the outbreak.”
It said semen has been imported for many years at the rate of around 250,000 straws a season.
“If semen was a significant risk factor, we could expect to see a lot more disease than we are.”
Manawatū/Rangitīkei Federated Farmers dairy chairman Murray Holdaway said while he was concerned no pathway had been found for the disease, he was in favour of the cull for eradication of Mycoplasma bovis.
“This is the only chance we will get of eradication and with gypsy day looming there was no option to delay.
“It will be hard for the farmers concerned to see their herds, some with generations of breeding behind them, being culled, but I think the biggest shock for the farmers concerned was probably when the disease was confirmed in their herds.”
He said the decision to send more than 22,000 dairy cattle to the meat plants was at least giving some certainty for the farmers for the future.
“In terms of the industry effects, there appears to be surplus cows for sale this year with very few buyers, and with what I consider to be a downsizing industry and many farmers planning on milking a few less cows because of the environmental pressures and the likely effects of the palm kernel penalties, there should be enough cows to fill the demand even with the cull.
“Farmers will probably have a more ‘closed’ operation where less grazing out will be done, less purchasing of stock including bulls for mating, and possibly less imported feed in order to reduce the risk of this or any other disease.”