Some in the industry try to claim that cage farms are more sustainable than free range or organic farms - and their bleating has been reinforced by a study presented a few years ago by Cranfield University in the UK.
It purported to show that organic egg production needs 14% more energy than non-organic and increases most environmental burdens by 10% to 33% (except pesticides), but the land area needed more than doubled. Comparing non-organic systems, it says that keeping 100% of the hens in cages incurs 15% less energy than 100% free range, with similar differences for most other burdens, although abiotic resource is 10% higher for caged birds and land use 25% less.
It seems to have been research which was designed to show that cage farms are environmentaly friendly!
What it clearly didn't take into account were things like the footprint created when the cage farm is initially established - the tonnes of concrete, steel, cooling equipment etc. etc. and the ongoing power costs associated with the massive sheds. (They don't have to worry much about cooling the sheds in the UK, but here right through summer the sheds have computer-operated climate control systems.)
At the Churchill Island Farmers' Market on Saturday we started promoting the low carbon footprint of our farm with leaflets like this: