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. It may also involve vent pecking immediately after oviposition, or picking at the skin on the head, comb, wattles, or toes. Cannibalism is the most severe outcome of both feather and vent pecking.
Etiology and Pathophysiology of Cannibalism in Poultry
No single cause of cannibalism in poultry has been identified, but genetics, crowding, excessive light intensity, and nutritional imbalances are correlated with its occurrence. Additionally, in overweight pullets entering egg production or hens in production, mucosa will protrude from the vent during and after egg laying, and this red tissue attracts pecking. Other factors are insufficient feeder space, mineral and vitamin deficiencies, skin injuries, and failure to remove any dead birds daily. In addition to the loss of birds due to pecking trauma, cannibalism often leads to transmission of infectious diseases (eg, erysipelas) and botulism.
Clinical Findings and Diagnosis of Cannibalism in Poultry
Cannibalism is more common when birds in floor systems lay their eggs on the floor in crowded areas. Birds have damaged feathers, and egg production usually drops. Increased incidence of prolapse is observed in flocks that vent peck. Cannibalism can also result in higher than normal mortality.
Lesions
Affected birds may be poorly feathered and have torn and damaged flesh. If the feathers or tissue are severely damaged, hemorrhage may occur. Appearance of blood on the exposed skin may induce more pecking and lead to death. Vent pecking is a separate form of pecking that also can be observed in well-feathered birds. Vent pecking occurs immediately after egg laying, and exposure of the mucous membrane stimulates pecking by other birds.
Control and Prevention of Cannibalism in Poultry
Control of cannibalism in poultry depends on correcting or reducing the above risk factors. These control measures must be implemented as soon as signs are noticed, because once this habit gets established it is difficult to eliminate. Interventions include correcting an inadequate diet, replacing mash feed with pelleted feed, rearing birds on floor litter rather than slats, reducing light intensity, and providing perches as a refuge for targeted birds. Environmental enrichment such as hanging white or yellow strings may be beneficial. Trimming the sharp distal end (tip) of the upper beak will decrease skin trauma from pecking; this may be done at 1 day of age and repeated between 6 and 12 weeks of age in maturing pullets or turkeys. The tip of the beak can also be treated by infrared heat on the day of hatching, which results in a shortened beak with minimal stress. Cauterization is required to provide hemostasis during beak trimming in older poultry.
