But commercial free-range flocks are also a long way short of welfare heaven.

Feather pecking is a multifactorial problem and a large number of risk factors have been identified for commercial flocks.

They are naturally resistant to fly strike-a characteristic that would be beneficial in commercial flocks.

Many commercial flocks, especially those producing sheep meat, utilize cross-bred animals.

Culling of infected birds is normally performed in infected commercial flocks.

The disease has not been found in commercial flocks, but some 11,000 privately owned birds have had to be destroyed since Oct. 1.

The outbreak is not a big problem in commercial flocks, but "in the country, every household has poultry," he said.

Second, the only cases of human transmission of bird flu have been where people were in close contact with commercial flocks.

It is one of the larger breeds, and is often used for cross breeding in commercial western flocks.

The mating period ranges from about 6 to 8 weeks in commercial flocks.