Southland and Otago farmers left with crops of potentially toxic swede are working on ways of mitigating the possible issues of using the crop to feed animals in winter.

Human error by seed wholesaler PGG Wrightson means more than 500 farmers are inadvertently growing the same variety of swedes this year that in 2014 were linked to the deaths of hundreds of dairy cows and some sheep.

Winton farmer Phil Garaway, who has 12ha planted the white-flesh HT S57 swedes, has been taking steps towards reducing the risk of using the swede, which, when grown in certain conditions, can be toxic to animals eating it.

"We've reduced our nitrogen input on to the swedes so we're not growing too much crop, and hopefully that's going to take some of the risk away from getting cows sick.


"We're also going to graze the crop at the start of the winter, rather than grazing it later on ... when we wanted to use it."

Garaway said he would also have to use more baleage while feeding on the swedes.

"We've gone up to about 30 bales a hectare, so that means putting in about an extra 90 bales of baleage over the crop, and that's just to increase the baleage percentage in the cows' diet and hopefully mitigate any factors around using the swede."

About 700 cows were wintering on-farm and it was not an ideal situation.

PGG Wrightson general manager David Green told farmers in Gore last week that compensation would be provided, and affected farmers could make claims against the company.

He hoped the company would be in a position to talk to affected farmers in the next few weeks.