Cannibalism in poultry

[2] Cannibalism can occur as a consequence of feather pecking which has caused denuded areas and bleeding on a bird's skin.

[4][5] There are several causes that can lead to cannibalism such as: light and overheating, crowd size, nutrition, injury, death, genetics and learned behaviour.

[6][1][2] Research has been conducted to attempt to understand why poultry engage in this behaviour, as it is not totally understood.

For example, hens in the wild often scratch at the soil to search for seeds, insects and even larger animals such as lizards or young mice,[7] although they are mainly herbivorous in adulthood.

High intensity light with prolonged exposure can lead to cannibalism of poultry in captivity due to the increase of stress and overheating that causes discomfort.

[1] An optimal flock size are either large flock of greater than 30 where the group is too large to recognize an established dominant bird and the social hierarchy breaks down, or a small group size where a social order can easily organize itself.

[1] This means the body cannot produce the amino acid and needs an external source to obtain its required amount.

[8] Methionine contains sulfur, which is necessary to grow feathers and this may explain the biological purpose for increased pecking.

When their diets lack salt, the gland produces the oily substances but without the salty taste.

Cannibalism among layer hen flocks is highly variable; when it is not problematic, mortalities among production systems are generally similar.

[10] Published data on the prevalence of cannibalism could be misleading due to the inclusion of vent-pecking by some researchers but not others.

Mortalities, due mainly to cannibalism, can be up to 15% in egg-laying flocks housed in aviaries,[11] straw yards,[12] and free-range systems.

In a study which examined 'skin damage' (most of which would have been caused by pecking) on hens at the end of their productive lives, damage was lowest in hens from free range systems, followed by barns, then furnished cages, and highest in conventional or battery cages.

Increased group sizes in larger cages or floor systems can elevate the risk of cannibalism and feather pecking, probably due to the spread of the behaviour through social learning.

For both spectacles and blinders, there are versions held in place by circlips in the nares of the bird, or others in which a pin pierces the nasal septum.

Farmers would have to choose between a trade off of either possibly having higher egg production with a high potential of flock death due to cannibalism, versus lower egg production with a lower risk of death due to cannibalism.

[6] To minimize cannibalism in domesticated poultry, different approaches such as ecology, environmental physiology, epidemiology, molecular genetics and ethology have been taken.