Group housing of growing rabbits: effects of stocking density and cage floor on performance, welfare and meat quality

Three hundred twenty rabbits weaned at 29 d (LW: 618 ± 65 g) were housed in group to evaluate the effect of stocking density and type of cage floor on behaviour, health status, growth performance, and carcass and meat quality. Rabbits were put in groups of 8 in 40 cages of two sizes (110 x 60 cm and 100 x 50 cm) allowing two stocking densities (D12, 12.1 rabbits/m2 vs D16, 16.0 rabbits/m2). Within density, two types of cage floor were compared (wire net vs slat) according to a 2 x 2 factorial arrangement with ten replications (cages). The rabbits were fed one single diet (CP: 17.6% DM, ADL: 5.7% DM, DE: 10.7 MJ/kg DM). No antibiotic was added to feed or water. Rabbit reactivity was controlled by tonic immobility and open-field tests at 51 and 66 d of age. Rabbit behaviour was video-recorded at 57 and 68 d of age for 24 h. Rabbits were slaughtered at 71 d to evaluate carcass and meat quality. The dimensions and the resistance to fracture of femur and tibia were measured. Sanitary status and growth performance were highly satisfying in all treatments. Mortality was 1.6% during the trial. Daily growth rate averaged 48.5 g/d and live weight at 71 d 2655 g, with a feed efficiency of 0.327. Carcass and meat quality, and bone fracture resistance were unaffected by housing system. The highest stocking density stimulated daily weight gain during the first two weeks of trial (51.4 vs 52.9 g/d in D12 and D16 rabbits; P<0.05) but tended to reduce feed intake in the last two weeks (185 vs 179 g/d, P=0.06). Video recording, however, showed no difference in behaviour between stocking densities. Although stocking density had no overall effect on final weight or feed intake, feed efficiency was higher in D16 rabbits (P=0.05). During the open field test, the D16 rabbits spent more time moving than the D12 rabbits (P=0.04), whereas no difference in rabbit reactivity was observed during the immobility test. The effect of the type of cage floor was weak and limited to a slight reduction in feed intake during the last two weeks of trial, and therefore an improvement in feed efficiency throughout the study (P=0.01), by rabbits reared on the wire net floor in comparison with rabbits reared on the slatted floor (179 vs 185 g/d; P=0.08). During the open field test, rabbits reared in cages with wire net floor showed higher exploration activity (P<0.01) without any difference in reactivity during the immobility test.