This conclusion is based in part on New Zealand research that found that the welfare of broiler chickens in New Zealand was on a par with world best practice.

NAWAC chairman, Peter O'Hara, says there was no evidence of compromised welfare that could be attributed to stocking density within the range of densities found in the project.

The research coupled with overseas research reports has enabled NAWAC to conclude that the management of environmental factors (temperature, humidity, noxious gas levels and litter quality) is the key to determining actual stocking density. Where management is good, a maximum density of 38kg liveweight per square metre is not associated with compromised welfare. NAWAC emphasises that the minimum standard in the Code specifies a maximum density.

"We are satisfied that the welfare of the birds can be maintained at an acceptably high level through good management and there are no scientifically sound reasons for abandoning it in favour of lower stocking densities or more extensive systems," Dr O'Hara says.

NAWAC will now undertake a complete review of the Code with a view to converting all of the minimum standards to a form that describes the welfare outcomes that chickens are expected to achieve. Each outcome will be accompanied by one or more welfare indicators that enable the achievement of the outcome to be measured or assessed. The review is to be completed by November 2009.

The broiler industry has already made significant steps towards the measurement of welfare outcomes and the introduction of independent audits of compliance with Code's minimum standards.

"NAWAC sees the full review of the code as an opportunity to examine whether the relationship between management factors and welfare outcomes requires further elaboration."