Post mortems done by local vet practices had, in some cases, shown severe liver damage and occasionally kidney damage, associated with the deaths.
Blood testing on some animals of all ages and classes of stock showed significantly elevated liver enzymes and compromised kidney function.
In the reported cases, clinical signs reduced once cows were removed from the swede crop.
DairyNZ was advising farmers and their staff feeding swedes to be extra vigilant and look out for signs of photosensitivity, weight loss, and ill thrift in their herds.
They should check all cows including young stock and any animals being fed swedes off-farm.
If signs appear they should take cows off the crop and contact a vet.
“If you have cows that are no longer on swedes but are still experiencing unusual animal health events, we recommend you contact your veterinarian.”
DairyNZ, veterinarians, and other rural professionals were working together to better understand the cause and provide further actions farmers could take to reduce the risk to their herds.
WHAT TO LOOK FOR
- Weight loss and ill-thrift
- Down-cows unresponsive to normal metabolic intervention, and
- Photosensitivity with signs including cows seeking shade, reddening of the udder and skin damage to white skin areas and restlessness shown by skin twitching, flicking of ears and tail, and irritability and stomping.
If signs appeared farms should, where possible, remove animals from crop and provide shade for any animal showing signs of photosensitivity.
If it was not possible to entirely remove swedes from the diet they should reduce the swede component by introducing or increasing other feeds.
“At this stage, given the limited knowledge that we have, we suggest that reducing the swede component of the diet to 50% or less may help.
“However, it is vital that farmers continue to monitor the herd and further reduce or eliminate the swede component of the animals’ diet if required.”
Providing alternative feed before the next break of swedes was offered might help reduce the incidence of clinical signs.
“If your cows are showing any of the above signs, contact your veterinarian for advice.
“Your veterinarian may advise that blood tests to determine any liver damage be performed. Post mortems on dead animals may also be recommended.”
