Psychological problems

Battery cages prevent chickens from engaging in most of their natural behaviors, including perching, roosting, dust-bathing, foraging, and exploring. It is nesting behaviors, however, that stand out as being particularly harmful to suppress in hens. Under normal circumstances, hens search out private places in order to construct nests before laying eggs. In battery cages, these desires are stifled, manifesting instead as repetitive stress-induced behaviors (such as pecking at other chickens); general restlessness; or “vacuum” nesting, where a hen essentially mimes creating a nest.

 

Given that laying hens can be compelled to produce eggs 300 days out of the year, this frustration is ongoing and a serious welfare concern.