Cannibalism in Poultry

What is Cannibalism?

Cannibalism is a problem that is associated with large poultry flocks where the birds kept in close confinement peck at associated birds. This can result in significant mortality within the flock when a wound is generated and it will also cause a decrease in egg production as the hen pecked birds become stressed. This is a vice which is usually precipitated by some aspect of management or environment which the birds are subjected to. Under the intensive management conditions used by today's industry this condition can occur in all ages of birds and in many species. It has been determined, however that the light breeds, such as the leghorns that are used in table egg production, are more susceptible than the heavier breeds. These lighter breeds are characterized by their flighty nature and are hypersensitive to environmental factors.

The behavioral problem of cannibalism in the poultry industry can include the following vices:

• Toe picking in chicks
• Feather pulling in older birds from the head, tail or body
• Vent picking in older birds

Feather pulling and vent pecking may be difficult and time consuming behaviors to observe in a flock, but the cannibalism can be clearly recognized when culled birds or moralities in the flock have had much of the intestine removed through the vent.

Cannibalism can also take a number of forms among the birds in a flock and can be presented in the following ways:

• A dominant bird pecking at a more submissive member of the flock
• Mutual pecking where birds in close proximity peck at each other
• On rare occasions young chicks may peck their own toes

What Are The Causes of Cannibalism In Poultry Flocks?

The causes of this vice are not well understood, but the onset of cannibalism has been attributed to a number of things which are outlined below:

• The problem may simply arise because of the normal pecking behavior of this type ofanimal when searching for food or exploring an environment. The birds are kept in barren, crowded conditions and may have little else to peck besides their pen mates. Once one hen has picked up this technique other hens, observing the behavior, will learn from the initial pecker and a serious episode will develop.
• A lack or a deficiency of nutrients in a poultry ration may result in the birds becoming irritated which can subsequently lead to cannibalism in the flock. Usually when diet formulation is involved in the outbreak the imbalance is in the protein or the sodium level of the ration. Deficiencies can also be caused by insufficient feeding and water space.
• An abrupt change in the palatability or form of a flock's ration may also be a contributing factor in the onset of cannibalism as the birds might impulsively seek alternative sources of food.
• Poor ventilation, high temperature, low humidity, excessive population density, and excess illumination are all factors in the flock's environment that may precipitate an outbreak of this vice, especially with the lighter breeds.
• During egg laying the cloaca may become damaged and distended especially with the passage of large eggs and this protrusion of the vent may be an attractant to other birds due to its stark color difference against the white body.

How Can An Outbreak Of Cannibalism Be Prevented In Your Flock?

The onset of this vice can be prevented by paying particular attention to the dietary factors (protein, sodium, and palatability), the environmental factors (ventilation, temperature, humidity, population density, and lighting) and the feeding and water space that is available for each bird. With highly intensive operations the light intensity should be reduced, perhaps by changing to a light which is of a red hue. The most common and cost effective mode of prevention is the use of beak trimming. Beak trimming is usually done at 4-6 weeks of age and the procedure requires that two thirds of the upper mandible be removed. Beak trimming is usually done with an electric debeaking machine which is available commercially. This procedure will not eliminate the abnormal behavior entirely but the birds are less able to inflict damage. A controversial approach is the use aluminum rings which are fixed to the upper beaks of the birds, but this has already been banned in some countries.

If an outbreak of cannibalism has already been initiated in a flock a manager may want to try to increase the searching aspect of feeding. Other control methods include increasing feed availability, reducing group size, adding litter, and providing distractants such as straw bales. Some managers of turkey flocks also will use a tar-like spray which deters cannibalism due to its offensive odor and taste.

It should be remembered when approaching a problem of cannibalism in the poultry industry that the best method of control is to prevent it from starting at all, since once it has begun it will be very difficult to stop.

References:

Austic, R.E., Card, L.E. and Nesheim, M.C.. 1979. Poultry Production. Twelfth edition. Bailliere, Tindall, London.

Fraser, A.F. and Broom, D.M.. 1990. Farm Animal Behaviour and Welfare. Third edition. Bailliere, Tindall, London. Jordan, F.T.W.. 1990. Poultry Diseases. Third edition. Bailliere, Tindall, London.