"The ancestor of the modern laying hen would lay at most a dozen eggs, once per year. Over the course of many years of selective breeding, the domesticated laying hen has been turned into a creature who will lay up to 300 eggs a year during her peak laying period. This high number has only been achieved through cruel genetic and behavioral manipulations. Normally, hens are instinctively driven to lay a number of eggs (totaling about 12) called a "clutch". After this number is achieved, the hen will stop laying eggs in anticipation of the hatchlings. This behavior holds true whether the eggs are fertilized or not. Egg farmers take advantage of this fact by removing any eggs that the hens lay. This forces them to continue to try to form their clutch of eggs in vain desperation. Sadly, they will be driven to madness as they attempt to form their clutch because their eggs are constantly stolen. Needless to say, this puts a tremendous psychological and physical strain on these birds. An animal that might otherwise live the better part of a decade is all but used up within a couple of years.
A hen in a backyard setting, given proper nesting materials will also attempt to form a clutch. If you chose to steal the eggs rather than leave them be, she will desperately attempt to form her clutch until she stops laying eggs or simply drops dead. By doing so, you are perpetuating the same cruel fate that she endured on the farm. The calcium needed to form just one egg can bind up ten percent of the calcium from her bones. Extended egg laying without proper mineral replenishment will lead to soft or fractured bones. When left alone, hens will actually eat their unfertilized eggs. This replenishes them with much needed minerals lost during the egg formation process." - Andy Williams