An in-depth scientific report into herbicide tolerant swedes that were linked to the deaths of hundreds of cattle in Southland is due out this week.
Early tests showed the herbicide tolerant swedes had very high levels of glucosinolates, which can be toxic to livestock - 16 times higher than would occur in a natural swede.
Herbicide tolerant swedes have been chemically mutated to withstand the herbicide - chlorsulfuron.
Hundreds of cattle died in Southland last year after eating them.
Dairy New Zealand says the report and a new advisory for farmers will be released this week.
The Green Party called for the swedes to be taken off the market until the testing was complete.
However, the Ministry for Primary Industries said it decided intervention at a product level would not resolve the problem.