Southern farmers remain without any real answers as to why hundreds of dairy cows fell sick, or died, last winter, as the third and final phase of testing begins.
The deaths of 200 cows and an associated photosensitivity - liver damage and peeling red skin on animals - of hundreds more have been associated with high levels of glucosinolates present in swedes fed to stock last winter.
But the industry-wide investigation's crop tissue tests, first expected to be completed in March, have only now begun, DairyNZ regional team leader for Southland-South Otago Richard Kyte said. It was the first time such testing had been done in New Zealand, he said.
''That is what's taken the time - getting the science right behind what we do.''
Crop samples were collected late last winter, both from farms where stock had been affected and unaffected by crops bearing the 27 identified glucosinolates believed to have contributed to the issues experienced by farmers, he said.
''Finding the different varieties was probably the hardest thing, because a lot of those swedes had disappeared.''
''[Stock] had eaten the evidence,'' Mr Kyte said.
It would take six weeks to run the tests, and analysis of the samples on the crop tissue, frozen in liquid nitrogen before being stored, could be complete by mid-July.
''We certainly don't want to over-promise,'' he said.
An analysis of a general survey of 400 farmers and in-depth surveys of 134 affected and unaffected farmers and 34 graziers last year as part of the working group's study was near completion and results were likely to be available by the end of May, Mr Kyte said.
Animal testing, including blood samples and post-mortems, were the first tests to be completed.
Those tests confirmed the cows were suffering liver-damage consistent with the known effects of high glucosinolate levels in swedes.
The accidental poisoning of cows was a huge problem last year, Mr Kyte said.
The deaths of cows alone would have cost farmers $400,000.
But at this stage DairyNZ could only educate farmers and ask them to remain vigilant.
''It was [huge] and we still need those answers.
''What we're talking to farmers about will be transitioning on to crops to minimise risk, and to be aware, looking at it for issues [monitoring stock for signs of illness].''
