A New Zealand vet and sustainable farming advocate says increasing use of imported GE feeds, that have been grown with the help of high levels of herbicides, could put the national dairy herd at high risk of botulism outbreaks.
There are multiple inquiries underway investigating how clostridium botulinum spores - which occur naturally in the environment - made their way into Fonterra whey protein and then its infant milk formula.
The contamination put children at risk and led to a world-wide product recall.
Frank Rowson is a Matamata vet and farm performance consultant and he says he's alarmed at the hundreds of thousands of tonnes of GE animal feed the New Zealand dairy industry is importing.
He says the increasing use of foreign GE animal feed, grown with high levels of glyphosate, puts dairy cows at risk.
He says it is toxic and wipes out the good bugs in the gut which keep clostridium botulinum at bay.
"It's being treated as if the dirty pipe is the primary source of this stuff. Well I don't think so, I think it's got to come from further back in the food chain and that would be through the milk, or hopefully not, through the water."
The New Zealand dairy industry hasn't vaccinated against botulism in a long time and it's not considered to be a problem with other livestock here either.
The New Zealand Veterinary Association says it won't comment on anything to do with botulism as the Ministry for Primary Industries has asked it not to do so.
