Australia's woes with its farm animals raised for their meat appears to be unending. After 21,000 Australian sheep were culled in October in Pakistan over suspicions of bacterial contamination, another 50,000 chickens in New South Wales were quarantined this week by state authorities.

The hens were quarantined because of suspicion that an unidentified strain of bird flu hit a chicken farm in Hunter Valley. However, the suspected virus appears not to be of the same strain as the H5N1 which killed 359 people worldwide in different avian flu outbreaks since 2003.

The NSW Department of Primary Industries said on Friday that it will cull the 50,000 chickens after lab tests on the virus samples conducted by the Animal Health Laboratory of the CSIRO in Geelong confirmed it is the H7 strain.

"The property has been placed under quarantine and initial tracing and surveillance is being undertaken to confirm that the virus hasn't spread. We currently have no evidence to suggest it has," NSW Chief Veterinary Officer Ian Roth said in a statement.

He disclosed that five outbreaks had hit Australia in chickens between 1976 and 1997, which were contained and successfully eradicated with no impact on health of Australians. Victoria was hit thrice, and NSW and Queensland once each. All five hits were caused by the same H7 strain, Mr Roth said.

The NSW Food Authority issued on Wednesday an advisory that while the H7 strain does not pose a risk to people, residents were cautioned not to eat raw, cracked or dirty eggs, and advised to cook poultry products thoroughly.

The advisory said that based on latest scientific evidence, the virus that causes bird flu is destroyed at temperatures above 70 degrees Celsius through careful cooking.