http://greeninc.blogs.nytimes.com/2010/04/13/mcdonalds-parries-on-cage-free-eggs/?scp=3&sq=burger%20king&st=cse
 

The board of directors of McDonald’s has recommended that the company’s shareholders vote against a proposal to require that 5 percent of the eggs purchased for the chain’s restaurants in the United States be the cage-free variety. McDonald assert there is no scientific reason to change 'Battery cages' to 'cage-free eggs' and no evidence to support the 'cage-free eggs' is better. However, many restaurant chains have changed their eggs to ‘cage-free eggs’ and The European Union (EU) already passed a law that bans conventional battery cages starting in 2012.

 Although there is no scientific evidence, most customers recognize 'cage-free eggs' is better than'Battery cages' and want it. In addition, it is too cruel to raise hens in 'battery cages' that afford a minimum of 72 square inches of floor space per hen just for human. Even the hens cannot fully spread their wings in the cage.

I also understand McDonald’s side because cheap price is one of biggest reason why people choose McDonald’s, and 'cage-free eggs' is more expensive than battery cages.  

However McDonald’s is very huge restaurant chain and have huge demand of eggs. Therefore, if McDonald’s makes new relationship with big farms which use the ‘cage-free eggs’, the farms would supply the huge demand to McDonald’s as cheaper price. Besides, I suggest McDonald’s serve two kinds menu for customers’ choice, cheaper one is by battery cages egg and a little expensive one is by cage-free eggs.