Stephen Hopkinson, of Taranaki Veterinary Centre, was one of the vets who arrived at the farm of Chris and Catherine Cook on the afternoon of December 5 to find many of the 600 cows on the farm down and bloating.
“Cows can eat a certain amount of urea but when they eat too much it gets converted into ammonia in the rumen and enters the bloodstream,” he said. “If too much is absorbed, more than the liver can cope with, it affects the brain and lungs.”
Early signs of ammonia poisoning were cows being wobbly on their feet, and sometimes aggressive, as well as salivating, bloating and having difficulty breathing.
“They can die very quickly, in 30 minutes, or up to two to three hours later, usually from fluid build-up in their lungs.”
Hopkinson said he and the other vets arriving at the farm near Manaia at first thought it was a bloat outbreak but after the cows did not respond to emergency bloat stabbing they realised it was ammonia poisoning. Emergency treatment for ammonia poisoning is emptying the rumen contents so no more ammonia can be absorbed into the blood system and neutralising the ammonia by adding four to five litres of vinegar into the rumen.
“We made the hole from the bloat stabbing larger to remove the rumen contents and then used that hole to pour the vinegar in,” Hopkinson said.
All up, 15 vets were at the farm from Taranaki Veterinary Centre and Coastal Veterinary Services, as well as several vet technicians.
“We even had our receptionists running around the supermarkets buying vinegar. It’s quite hard to buy that much vinegar.”
He said about 40 cows were given the treatment, of which 17 lived. That day 120 cows died and a further two died a few days later.
“The lesson is only use containers for what they are intended for.”
Family spokesman John Murphy, Catherine Cook’s brother, said a 5000-litre plastic container which had been used to store urea was used to top up water troughs on the farm after it had been thoroughly washed that morning.
“It was the first nice day of summer and the cows were drinking water faster from the troughs than the farm’s water system could keep up with,” he said. “The plastic must have absorbed the urea.”
He said the Cooks and their staff had been devastated by the loss of their cows.
“We have an awesome farming community here and they have really helped out. They’ve been amazing.”
He said about 80 cows had been either gifted to the Cooks or were made available for lease until the end of the season.
The Ministry for Primary Industries (MPI) is investigating the deaths and a report is due out early in the New Year. A decision would be made once the investigation was finished whether it would be made public.