Chair of the New South Wales Farmers' Association's Egg Committee, Bede Burke, says the destruction of 400,000 egg-layer hens caught up in a bird flu outbreak will take about two weeks.

The Tamworth-based poultry breeder says it is one of the single biggest culls ever undertaken on one property, with the replacement cost of the birds estimated to be at least $4-million.

Hong Kong has announced it will temporarily suspended poultry imports from New South Wales following the highly-pathogenic H7 outbreak at Young, in the state's Central West.

Bede Burke says a sizeable amount of the financial burden will be picked up by the Commonwealth government in a cost-sharing arrangement.

"To get that farm up and running is $4-million, so it's a huge loss and a huge commitment," he says.

"My understanding again is if it's the high-pathogenic avian influenza then industry picks up a much lower cost in terms of the ratio; government 80 per cent, industry 20 per cent, so that could be a favourable outcome for industry."