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Hens have been bred now that lay 100's of eggs a year; and they don't seem to miss the nesting instinct. Food goes in one end and eggs come out the other Rather unnatural in such quantity, but the hens seem contented enough. I have a lot of friends who keep free range chickens, there's no shortage of eggs.
Going to disagree with some of this - hens do still naturally try to hatch eggs - its only the act of daily egg removal that keeps them laying - its a completely natural behaviour. They are constantly trying and failing to complete a clutch. Let them complete that clutch and they will quickly go broody, try to hatch the eggs (and succeed if a cockerel is present) and stop laying.
Chickens live from six to ten years - but almost all egg laying birds are killed at two years as after that they cannot keep up the egg laying speed and the economics don't work - so they are slaughtered (and almost invariably not eaten as they are not nice tender meat birds).
Its a funny old world where the things like dairy and eggs are, to my mind, the cruellest parts left of farming - rather like the growing of vegetables causes the greatest destruction of nature and wildlife.
Still, far be it from me to argue with food choices - some people eat brussel sprouts - I'd rather have a cheese omlette any day!