Bicellular cage vs. collective pen housing for rabbits: Growth performance, carcass and meat quality

The aim of this study was to compare the growth performance, slaughter results, and carcass and meat quality of rabbits reared in different housing systems. To this purpose, 456 Hyplus crossbred rabbits were reared from weaning (35 d of age) until slaughter (77 d) in 40 bicellular wire net cages (28×40×28 cm3; 2 rabbits/cage; 18 animals/m2); 4 small collective pens (1.40×1.20 m2) at low stocking density (20 rabbits/pen; 12 animals/m2); 4 small collective pens at high stocking density (27 rabbits/pen; 16 animals/m2); 2 large collective pens (1.40×2.40 m2) at low stocking density (40 rabbits/pen; 12 animals/m2); and 2 large collective pens at high stocking density (54 rabbits/pen; 16 animals/m2). The housing of rabbits in collective pens decreased final live weight (2839 vs. 2655 g; P<0.01), daily weight gain by 10.0% (P≤0.01), and feed intake by 10.7% (P=0.001), compared with rabbits housed in bicellular cages, without affecting feed efficiency. At slaughter, the rabbits from collective pens showed lower live weight, carcass weight, dressing percentage (60.5% vs. 59.5%), dissectible fat proportion (3.0% vs. 2.1%), and hind leg muscle-to-bone ratio (7.53 vs. 6.63) compared with those from bicellular cages (P<0.001); the former rabbits had shorter (P<0.05) and thicker femurs (P=0.01). Within the collective pens, the increase in the stocking density from 12 to 16 rabbits/m2 increased only the slaughter dressing percentage (59.4% vs. 59.8%; P=0.05) and the femur resistance to fracture (39.9 kg vs. 45.5 kg; P<0.01). Pen size affected meat quality: meat pH was lower (5.72 vs. 5.76 for Longissimus lumborum muscle; 5.98 vs. 6.00 for Biceps femoris muscle; P=0.05) and cooking losses were higher (L. lumborum: 30.0% vs. 28.8%; P<0.01) for rabbits reared in small pens compared with those in large pens. Additionally, femur maximum diameter was lower in rabbits kept in small pens compared to those in large pens (P=0.05). In conclusion, rearing rabbits in collective pens impaired growth performance and slaughter results compared to rabbits kept in bicellular cages, regardless of stocking density or pen size. However, the skeletal development of the animals improved in collective systems, whereas meat quality was only slightly affected by the housing system.