Some egg associations are still speaking out against the move, saying it will not improve welfare, and Egg Farmers of Canada have come out in favour of enriched colony cages as part of the transition to higher welfare production methods.

However, a member of McDonald’s management said that enriched housing means nothing to consumers, and all the public wants is hens to be out of cages.

British egg producers are looking across the pond with interest, as I heard at the British Pig and Poultry Fair last month.

It is not long since farmers made huge investments to transfer away from barren battery cages to enriched colony cages, to comply with European rules.

There are worries that retailers may soon want to move to entirely cage-free in Britain, too. Once one retailer starts to do this, the American example shows that other retailers may follow, and this would make all that investment pointless as they then have to switch to yet another production method.

Aldi UK has already announced a move to entirely cage-free, with the NFU raising concerns that poultry farmers’ investments in enriched housing may be overlooked.

But will all this actually improve welfare for the hens?

Poultry expert Guillermo Zavala is worried that hens roaming outside are more vulnerable to all kinds of diseases and infections that cause them suffering, including avian influenza. This may mean more medication needs to be used on these birds – but there is also consumer pressure to remove antibiotics from poultry production, limiting vets’ options.

Free-range hens also tend to engage more in feather pecking, with adverse consequences for bird welfare.

On the other hand, Dr Zavala says birds subject to any form of confinement, not just in cages, will be subject to physical trauma, as they knock themselves more and there is more competition.

Leaving us with the question, what is welfare? There seems to be no perfect answer for the hens yet. Research and good management are needed to make welfare the best it can be within the systems that we have available.