Fear level and behaviour of growing rabbits housed in individual, bicellular and collective cages

During growth (from 27 to 75 d of age), 384 rabbits were kept into 72 individual cages (72 rabbits), 48 bicellular cages (2 rabbits/cage; 96 rabbits) and 24 collective cages (9 rabbits/cage; 216 rabbits). To evaluate the effect of the housing system on fear level and behavioural pattern of rabbits at two ages (39-45 d and 66-73 d of age), the tonic immobility test and the open field test were performed and behaviour was video-recorded. At the tonic immobility test, the number of attempts to induce immobility was lower (1.38) and the duration of immobility was higher (47.8 sec) in rabbits from individual cages than in those from bicellular (1.72 number of attempts and 25 sec of immobility) and collective cages (1.99 number of attempts and 25.0 sec of immobility) (0.05<P<0.01). During the open field test, rabbits from individual and bicellular cages showed higher latency (38.8 and 40.3 vs. 27.0 sec), lower number of total (73.3, 81.7 and 91.9) and central displacements (3.6 and 2.8 vs. 5.4), ran for a shorter time (11.8 and 13.6 sec vs. 17.7 sec) and bit less some parts of the pen (5.5 and 9.1 sec vs. 28.2 sec) compared to rabbits kept in collective cages. During the 24 hours, rabbits in individual and bicellular cages spent less time for allo-grooming (0.34% and 0.19% vs. 1.44%), moving (0.74% and 0.60% vs. 1.32%) and running (0.08% and 0.03% vs. 0.21%) than rabbits in collective cages (0.01<P<0.001). The lowest numbers of rearing and hops were observed in rabbits kept in bicellular cages. In conclusions, rabbits in individual cages exhibited the highest fear level, a reactive coping strategy and an incomplete behavioural pattern; rabbits housed in collective cages showed the lowest fear levels, had proactive coping strategy and the possibility of expressing more behaviours; rabbits in bicellular cages exhibited a not consistent pattern of fear in the tonic immobility and open field tests and a less defined coping strategies. These rabbits were likely in a less stressful condition compared to animals in individual cages since locomotory possibilities were even more limited, but social contacts were allowed.