Effects of feeding corticosterone and housing conditions on feather pecking in laying hens (Gallus gallus domesticus)

Feather pecking (FP) and cannibalism in laying hens are disadvantageous to the well-being of the birds. We investigated whether stress could be proposed as a trigger for the development of this abnormal behavior. From Week 11 to 19 after hatching, 16 groups of 15 or 16 hens (white Lohman Selected Leghorn hybrids) were kept in pens with or without foraging material (litter) and fed a diet containing corticosterone (C, 1.5 mg/bird/day) or no C. Birds fed on C had reduced values for weight gain and egg production, prolonged tonic immobility (TI), higher heterophil/lymphocyte ratios (H/L) and higher serum C concentrations. On litter, C-fed birds developed significantly higher rates of FP than when not fed C. However, birds kept on slats also developed high rates of FP but without being fed C. Feeding C to these birds did not significantly further increase the rates of FP. We concluded that FP may develop as a response to increased blood C concentrations, but that housing conditions restricted in relation to foraging material, may as well induce FP in the absence of increased C levels. (C) 2001 Elsevier Science Inc. All rights reserved.