battery cage

A battery cage is a wire or plastic enclosure, typically measuring 45 by 45 centimetres in floor area, designed to house one hen for commercial egg production. The cage provides minimal space, usually between 550 and 900 square centimetres per bird depending on jurisdiction and design. The structure consists of sloped wire floors that allow droppings to fall through for ease of cleaning, automatic feeding troughs along the front, and water nipples or troughs for hydration. Eggs roll down the sloped floor toward a collection area outside the cage.

Battery cages operate on the principle of maximizing output per unit of space and labour. Birds cannot spread their wings, dust-bathe, or exhibit many natural behaviours, but they do convert feed into eggs with reasonable efficiency under controlled conditions. Multiple cages are stacked vertically in rows, creating a battery formation, with conveyor systems or manual collection retrieving eggs continuously. Feed and water are delivered mechanically, and waste drops to collection belts below.

Decline and alternatives

Conventional battery cages have been phased out or banned in the European Union since 2012, and restrictions are increasing across other markets. Critics cite poor animal welfare and higher rates of bone fracture, feather loss, and respiratory disease. Enriched cages, slightly larger enclosures with perches and nesting boxes, have partially replaced them in some regions. Free-range and cage-free systems now compete commercially, though they require more floor space and different management practices.

The term battery, drawn from military artillery batteries (multiple guns firing together), reflects how these cages are deployed: many units functioning in parallel to deliver consistent volume. Early versions appeared in the 1930s and became dominant through the 1960s and 1990s when labour costs and space premiums favoured density over individual bird welfare considerations.