A working group set up to get to the bottom of cow deaths linked to eating swedes in Southland is to meet today.
The group includes local vets, farmers, industry groups and the PGG Wrightson Seed company and will call on plant and animal experts.
It follows the death and illness of hundreds of cows that have grazed on swedes, mostly a herbicide tolerant variety.
DairyNZ has sent an email survey to more than 2500 farmers in Southland and South Otago to find out if they have been affected.
The working group's chair, DairyNZ's southern regional leader Richard Kyte, said it wants to find out the scale of the problem and come up with advice on what to do about it.
"We've been talking around 150 (of deaths), but we've been hearing from vets definitely over 200. There's also cows that have been euthanised and there are also cows out there with issues. Whether they'll recover or not is a matter of time, and we're working through that with vets to see where the cut-off line is there as well.
"I'm hearing every few days a farmer here or there will be saying they've lost 20 to 30 cows, so, it's hard to put a number of it and it'll be good to actually sit around the table and try and get some numbers."
Mr Kyte is asking farmers to respond to the survey and let the working group know if they think their stock have been affected.
Getting the right advice is essential for farmers, he said, as they would need to make decisions soon on planting feed crops for next winter.