Effects of cage density on fear-related behavioral response and activity of layers.

Two experiments were conducted to study the effects of cage density on fear-related behavioral response and activity of White Leghorn layers. In Experiment 1, 20-wk old pullets were placed into 30.5 x 50.8 cm cages at the rate of one, two, three, and four birds per cage for Treatments 1, 2, 3, and 4, respectively. In Experiment 2, birds were placed into cages (30.5 x 50.8 cm) at the rate of one, two, three, four, three, two, and three birds per cage for Treatments 1, 2, 3, 4, 5, 6, and 7, respectively, at 20 wk of age. At 28 wk of age, one bird was removed from each cage in Treatment 5, and one bird was added to each cage in Treatments 6 and 7. Fear-related behavioral response of the birds, as determined by the duration of induced tonic immobility (TI), and bird activity, as determined by the head movement (HM) count, were measured at 52 wk of age in Experiment 1, and at 29, 36, and 52 wk of age in Experiment 2. Increasing cage density had no effect on fear-related response of the birds in both experiments. Cage density effect on bird activity was not consistent. In Experiment 1, HM count was not affected by cage density, whereas in Experiment 2, pullets in the multiple-bird cage had a lower (P < or = .05) HM count (three-period average) than the birds housed individually. There was no correlation between the duration of induced TI and HM count in both experiments.(ABSTRACT TRUNCATED AT 250 WORDS)