DairyNZ’s Southland regional leader Richard Kyte says DairyNZ interviewed 134 affected and unaffected farmers and 34 graziers last year as part of its study into why many cows became ill after feeding on swedes last season. The detailed interviews followed a general short survey of all dairy farmers that generated more than 400 replies. Analysis of all the survey data is now nearly complete.
“We interviewed farmers across the region to help us understand whether farm management practices may have been a contributing factor. We had some delays in getting the data from the field as farmers got busy just as we started approaching them for information. Until all this analysis is complete, we won’t know if we need to gather more background information. We are expecting to have the results of all this work released to farmers from around mid to late May,” he says.
DairyNZ has already released the results of its analysis of the blood and autopsy samples it collected from dairy cows. Richard says those findings indicated that the cows experienced liver damage consistent with known liver damage associated with cows grazing brassica forage crops, except the visible signs of illness seemed to be more severe.
Meanwhile, the analysis of plant material samples taken from Southland swede crops last year as part of the DairyNZ study is taking longer than expected because of delays in getting the necessary testing equipment from overseas.
“The testing of the plant samples has proved a real challenge for us. This has never been done before in New Zealand so we’ve had to organise an accredited commercial testing facility for glucosinolates (GSLs) – the compounds we are testing for in the swedes,” says Richard.
“We needed the most up to date technology to provide us with the best chance to identify the issues with these swedes. The testing has to stand up to our high standards for scientific rigour. We have identified 27 GSLs that could have contributed to the issues with the swedes and we had to develop benchmarks to enable us to measure them correctly. We also needed the right equipment in place. These have had to be sourced internationally from three countries and that took quite a lot of time – much longer than we’d expected,” he says.
“Now that the equipment has arrived we can start testing and we expect that process to take around six weeks. So the analysis of the plant samples should be complete by the end of May and the interpretation of that data by mid-July.”
Richard says the cross-sector industry advisory group that he chairs has released advice to help farmers make key decisions this winter around transitioning and managing crops to feed their cows.
“There’s already a lot of information on the DairyNZ website to help farmers – www.dairynz.co.nz/swedes. We’re conscious that we need to help farmers with their decision-making while we wait for the full study to be completed,” he says.
“Our key message for farmers is to be cautious when transitioning cows on to brassicas and fodder beet. Transitioning your cows well from grass to brassicas and fodder beet and offering the correct ratio of crop to forage supplement – both are essential. When allocating swede crops, we’re advising farmers to be cautious if they see the plant showing signs of developing flowerhead, which increases GSL content, or if leaf regrowth is occurring.”
DairyNZ communications manager
tel 027 703 0211