Egg producers say they are being ordered to phase out battery cages in a "brutally short" time and the transition could cripple the industry.
The government on Thursday announced battery cages would be banned from 2022.
From Friday, no new battery cages can be installed and Primary Industry Minister David Carter says about 45 per cent will be gone by 2018.
The Egg Producers Federation (EPF) says the reality is that the phase out has to be completed in four to six years, not 10.
"The formula is, quite frankly, harsh and punitive," EPF chairman Michael Guthrie said on Friday.
"The estimated cost starts at $150 million and goes up from there - a significant number of farmers will quit the industry."
Mr Guthrie says the programme simply can't be achieved, and Mr Carter will be told that.
About 80 per cent of New Zealand's 42 egg producers use battery cages, and more than a billion eggs are sold each year.
The new welfare code says hens must be kept in larger colony cages, in barns or on free ranges.
Mr Carter says scientific evidence, and strong public opinion, have made the change necessary.
Mr Guthrie says the industry accepts that and wants to get away from the connotations of battery cages, but isn't being given enough time.
The Green Party says all types of cages should be banned and the welfare code still allows hens to be kept in cruel conditions.