When an egg is laid, the vagina everts through the cloaca to deliver the egg. If there has been injury to the vagina, such as from a large or double-yolk egg, or if the hen is fat, the vagina may not retract immediately, leaving it exposed for a short time. This may result in cannibalism Cannibalism in Poultry Feather pecking and cannibalism are major welfare problems. Cannibalism stems from aggressive behavior of chickens and turkeys that may begin with feather pecking by socially dominant birds... read more . When the protruding organ is pecked by other hens, the complete oviduct and parts of the adjacent intestinal tract may be pulled from the abdominal cavity (“peckout”). Bleeding from the vent is observed as a result of pecking. Alternatively, the vagina swells, cannot retract, and remains prolapsed (“blowout”). The hen dies from shock.
Prolapse has been associated with:
poor body weight uniformity
early laying (inadequate body size)
Cannibalism may be prevented by beak trimming, managing light intensity, maintaining appropriate stocking density, and avoiding nutritional deficiencies.