Ethological, Clinical, and Neurobiological Studies on Cannibalism in Black-Necked Pheasants (Phasianus colchicus) and Correction of Behavioral Disorders by Applying Nutritional Supplements

Cannibalism in Black-necked pheasants is a problem in aviary rearing, and an effective solution is still lacking. We performed the present study to investigate the potential of using tryptophan or silymarin to suppress cannibalism. The following types of investigations were performed: evaluation of the pheasants' harmful behavior manifestations, and evaluation of the clinical forms, severity and localization of injuries of feathers and tissues, and neurohormonal manifestations. Additionally, the potential of cannibalism control in pheasants by supplementing tryptophan and silymarin to the birds' diet was investigated. Ethological studies have shown a low intensity of feather pecking in pheasants without cannibalism manifestations. In pheasants with pronounced cannibalism, severe forms of feather and tissue pecking were observed in the head, back, wings, and rump areas, as well as specific forms affecting the tail feathers and the cloaca. Tryptophan and silymarin significantly reduced the levels of injurious pecking in the studied game birds and improved the healing of the lesions. The blood serotonin and dopamine levels in pheasants manifesting cannibalism were significantly lower than those in birds which did not show such behavior. The addition of tryptophan or silymarin to the diet of birds exhibiting cannibalism resulted in significantly increased plasma concentrations of serotonin or dopamine.