A second major outbreak this year of botulism has occurred in cattle on the North Coast, this time involving the deaths of 44 adult milking cows in a large dairy herd at Comboyne near Kempsey.

It follows a botulism outbreak in June, when 98 cows died on a dairy farm at Grevilia, near Kyogle.

NSW DPI Regional Animal Health Leader Paul Freeman said all cattle on the Comboyne farm have now been vaccinated against botulism, so no further deaths are expected.

Botulism is a disease that can occur in cattle when they eat botulinum toxin produced by bacteria growing in rotting animal or vegetable material.

“Outbreaks of botulism have become more common in the intensive animal industries in recent years, in most cases due to the contamination of feeds such as silage,” Mr Freeman said.

“Sources of rotting material in stored silage have in the past included snakes and other animals,” he said.

“These animals are sometimes killed by slashers and incorporated inside large round bales or pits of silage.”

Mr Freeman said animal carcasses and chicken litter were two other known risk factors for botulism.

“Animal carcasses should either be buried, or burnt and buried, or fenced off, so that cattle are unable to access the burial area,” he said.

Mr Freeman said if poultry litter was used as farm fertiliser, it was important that:

• litter stores are not accessible to cattle;
• any bird carcasses be removed prior to spreading on pasture, and;
• cattle be withheld from grazing for at least 21 days after poultry litter is applied to pasture.

It is an offence under the Stock Diseases Act for anyone to feed, cause or permit stock to feed on animal carcasses and chicken litter.

Mr Freeman said early signs of botulism in cattle varied from sudden death to a slowly progressive paralysis where infected animals could take several days to die.

“Once cattle go down their recovery is unlikely,” he said.

Vaccination is a cost-effective method of avoiding a botulism outbreak.

Contact Paul Freeman, Wollongbar, (02) 6626 1200.