I picked up this interesting piece of information. It comes from a 2007 research report.
Williams, senior research fellow at Cranfield University recently carried out
a DEFRA-funded project that calculated the life cycle assessment (LCA) of
different farming systems. The concept looks at the consumption of natural
resources such as minerals and fossil fuel. "Poultry is the market
winner in energy performance," said Dr Williams. "The sector should
give itself a pat on its back." However, Dr Williams stressed that
Global Warming Potential (GWP) varied depending on the different types of poultry
farming methods. If the egg industry was to move towards all cage production,
GWP would fall by 10% while going all free range would increase it by 10%.
More significant is that going organic would result in a 40% increase in GWP.
He explained the main reason was that organic chickens use more energy,
having a lower feed conversion, so they eat more feed. Feed accounts for most
of the energy required and is a key driving factor for poultry. With meat,
organic also comes out worst because of the longer life-span of birds, again
leading to a greater lifetime feed consumption.
Put in language I can understand it means " eat a cage egg and help save the world ". I guess it comes down to human population increase. If we continue at our present rate there will be standing room only for ourselves and the chooks.