Taste aversion learning to eliminate feather pecking in laying hens, Gallus gallus domesticus

Abstract

Feather pecking in laying hens is a redirection of normal pecking behaviour. There is clear evidence that severe feather pecking is influenced by the motivational system of foraging and feeding. Feather pecking is positively associated with feather eating, indicating that feathers are seen as a feeding substrate by laying hens. Feed choice may be affected by many factors, including learning processes. In this experiment, feathers of other birds were made distasteful by adding a bitter taste (quinine). We investigated whether laying hens could detect quinine and learn to avoid the feather cover of conspecifics. We also examined the effects of quinine on birds' own feather-related activity (preening). Six groups of 10 high feather-pecking birds and six groups of 10 low feather-pecking birds were kept on litter. Half of these groups were quinine treated. Each bird of the quinine-treated groups was individually sprayed with a quinine solution. We investigated whether the presence of quinine on birds' feather cover affected severe and gentle feather pecking, aggressive pecking and preening. In the present study, severe and gentle feather pecking decreased when feathers were made distasteful, suggesting that learning occurred. Furthermore, the results suggest that quinine is an effective reinforcing agent to alter feather-pecking behaviour. Distasteful feathers did not influence preening, whereas aggressive behaviour was reduced. Our experiment showed that birds in the quinine treatment were able to learn that feathers from conspecifics were not attractive to peck at and they learned to avoid them for a period of time.