The European Union banned chicken battery cages last year. Typically the wire mesh cages gave 4-5 hens only the space covered by a piece of A4 paper in which to survive. In the US eight birds are crammed into the same space. Such treatment is literally a living nightmare. These hens never experience natural light, fresh air, earth beneath their feet, or stretch their wings before they are taken to the slaughterhouse. An improvement, but not much, is the colony cage which is sometimes called the "enriched cage" since they are slightly less crowded (20% more square space than an A4 page) and allow some movement. But hens cannot perch or avoid hen pecking. Modern laying hens are bred to produce a unnaturally high number of eggs that deplete the animals calcium stores resulting in osteoporosis and fractures. Battery raised eggs are noticeably inferior.
The ideal way to raise chickens is the free range method, that costs more per egg so is incompatible with the strictures of unethical capitalism, but the hen giving up her eggs for human consumption leads a life more approaching normality. In a word, the hen is happier. A free-range hen lives in a shelter where she has a nest in which she can do her duty quietly and with some comfort. During the day she can roam her enclosure, peck the ground, flap her wings, and occasionally even get off the ground. Her interactions with other birds are less stressful. She can have a dustbath if she likes. The difference can be likened to heaven and hell: as a consumer you have a choice, support hell or help heaven.