The Ministry for Primary Industries is to bring in new rules to ensure an imported feed is free of sharp pieces of metal that can perforate an animal's stomach wall.
Palm kernel expeller (PKE) is an increasingly popular dairy cattle feed imported mainly from Indonesia and Malaysia.
At present 60 percent of PKE is screened in New Zealand with the remainder screened in the country of origin. The new rules will make it mandatory for all PKE to be screened here by its importers.
The ministry's acting deputy director-general of standards Ben Dalton says so-called "hardware disease" has been a source of concern in the dairy industry for a couple of years.
He says two cases have been through the legal system but it is difficult to diagnose and therefore probably under-reported.
Mr Dalton says PKE is increasingly the supplement of choice for farmers. Last year 1.5 million metric tonnes were imported and this year it's projected 2 million metric tonnes will be brought in.
He says the amount of imported PKE will increase as the years go by and so it's logical that over time it will become more of an issue.
Mr Dalton says the 4mm mesh screening in New Zealand will be accompanied by a requirement for better record keeping so it's easier to trace the source of any contaminated PKE.
He says the metal could come from anywhere in the supply chain, which is another reason screening in New Zealand should minimise contamination before the PKE is delivered to the farmer.
The Veterinary Association says while it is a good precaution to screen all PKE feed on arrival in New Zealand, contamination by shards of metal is not a frequent cause of a potentially lethal disease in cows.
The association's Waikato-based dairy cattle spokesperson, Neil McPherson, says cows have always been susceptible to hardware disease, ingesting bits of metal that have been lying on the ground as they graze.
"Certainly in our experience here in the Waikato we haven't had anything that we could specifically relate to the palm kernel. But I think having really good standards and having the specification of four millimetre (mesh screening) is a very good thing to have."
The ministry wants feedback on the draft rules by 6 March.
