Behaviour and welfare of growing rabbits housed in cages and pens

The present study compared behaviour, fear and stress levels of 456 crossbred rabbits reared in bicellular wire-net cages (2 rabbits/cage) with top and wire floor or open-top collective pens (20 to 54 rabbits/pen) with wooden slatted floor. The effect of pen size (small vs. large) and stocking density (12 vs. 16 rabbits/m2) in collective pens was also evaluated. The rabbits kept in collective pens rested more than those in bicellular cages (82.1% vs. 77.6% of observed time; P<0.01), spent less time feeding (7.8% vs. 10.9%), allo-grooming (0.65% vs. 1.58%) and more time moving (0.81% vs. 0.35%) (P<0.01). The percentage of rabbits sensitive in the tonic immobility test was lower in rabbits kept collectively compared to those in bicellular cages (76.6% vs. 93.8%; P=0.03). In the open field test, the rabbits kept in collective pens moved less (40.4 s vs. 57.2 s; P<0.001) and explored the arena for a shorter time (345 s vs. 371 s; P<0.001) than rabbits housed in bicellular cages; instead, these rabbits stood still for a longer period of time (82.1 s vs. 38.7 s; P<0.001). The rabbits kept in collective pens displayed a higher hair corticosterone level (15.7 ng/g vs. 6.7 ng/g for rabbits from the cages; P<0.001). Within collective housing systems, stocking density had no effect whereas increasing pen size numerically reduced the time rabbits spent eating (8.30% vs. 6.55%), self-grooming (6.39% vs. 5.47%) and time spent resting (81.1% vs. 84.1%). In conclusion, rabbits housed in collective pens displayed a more complete behavioural pattern, despite resting more; they were more bold toward humans, but more fearful in a new environment than rabbits from cages. In the tested conditions, pen size and stocking density within collective systems exerted only a weak effect on behaviour, fear and stress levels of meat rabbits.