Anatomical consequences of partial beak amputation (beak trimming) in turkeys.

A detailed anatomical study was made of the effects of trimming the upper beak of turkeys. The anatomy of the normal beak was compared with that of beaks from birds which had been trimmed by one of three methods, all commonly used in the poultry industry: the Bio-Beaker which passes an electric current through the premaxilla, secateurs, or a heated blade debeaker. All three resulted in the loss of significant amounts of beak tissue. By 42 days after trimming the beak had healed with extensive regrowth, including bone and cartilage formation, and the pattern of regrowth was similar after all three methods. In the normal bird the dermis at the tip of the upper beak contains large numbers of nerve fibres and sensory receptors, but in the beak-trimmed birds the dermal tissue, although well supplied with blood vessels, was devoid of afferent nerve fibres and sensory nerve endings. In contrast with the results of previous studies with older chickens there was no evidence of neuroma formation. Trimming with secateurs was the most precise method. The heated blade damaged additional tissue close to the position of the cut, and the BioBeaker produced the most tissue damage. Behavioural studies suggested that the effectiveness of beak trimming in controlling feather pecking depends on the extent of the tissue damage.