Comparison of individual and social feather pecking tests in two lines of laying hens at ten different ages

Abstract

The aim of this experiment was to select a suitable test to measure feather pecking in laying hens. Pecking behaviour in individual and social feather pecking tests was compared with pecking behaviour in the homepen. Two lines of laying hens were used that differ in their propensity to display feather pecking: the high feather pecking (HFP) and low feather pecking (LFP) lines. Six groups of five birds per line were housed on wood shavings with ad libitum food and water. From 7 to 34 weeks of age, every 3 weeks pecking behaviour in the homepen was observed and three feather pecking tests were conducted as well: one individual test with a bunch of feathers (10 min) and two social tests (in random order), one with and one without a bunch of feathers (30 min with whole group). Observations focused on gentle and severe feather pecking, bunch pecking, ground pecking and preening. In the individual test, general activity and vocalisations were recorded as well, to measure the response to isolation. In general, HFP birds showed more gentle and severe feather pecking than LFP birds, whereas LFP birds showed more ground pecking and, unexpectedly, more bunch pecking. Birds that showed gentle feather pecking in the homepen also showed gentle feather pecking and bunch pecking in the social tests over all ages. Severe feather pecking in the social test with a bunch of feathers corresponded with severe feather pecking in the homepen. Bunch pecking in the individual test was not a reliable measure for feather pecking in this experiment. An increasing number of vocalisations in the HFP line and a decreasing number in the LFP line indicated a difference in reaction to the individual test. In conclusion, gentle and severe feather pecking and bunch pecking in the social test corresponded best with homepen behaviour, whereas bunch pecking in the individual test did not.