Farmers in New Zealand are being advised to keep a close watch on cows that have been grazing or are grazing on swede crops after reports hundreds of dairy cow deaths.
David Green, PGG Wrightson Seeds says: “We don’t have a total picture yet on the extent of the problem. We think between 30 and 50 farms are affected and the illnesses range from mild photosensitivity and liver damage right though to death. It is likely 100s of cows will have been affected.”
“The mild winter and lush growth of leaf material on brassica crops, especially swedes, has caused problems where dairy cows have been introduced onto the late winter swedes after wintering on other types of crops,”
“With extra swede leaf material available due to the unusually mild winter it appears some cows have consumed more leaf and less bulb than normal. Consuming more leaf, less bulb and less supplementary feeds during wet August conditions has combined to amplify risk factors that can cause liver disease.
Most of the affected farms are in central and lowland Southland.
“As soon as the incidents of sick animals were reported we began working closely with farmers, vets and suppliers to investigate the problem and explore solutions,” David says.
“Blood tests and post-mortem examinations of affected animals have shown signs of liver disease. Other signs have been photosensitivity and increased susceptibility to infections.”
Initial reports from veterinary advisors suggest glucosinolate toxicity is the cause of the illness.