Alternative pen housing system for fattening rabbits: effects of group density and litter
The purpose of this experiment was to verify the compatibility of a group housing system, from weaning to slaughter, with the rabbit modern productive standards, evaluating the effects of different stocking densities and type of litter on health, performances and some aspects of carcass and meat quality. Two experiments were carried out. In the first, 184 rabbits were housed in two-places, either wire mesh cages (16/m2) or in 1.0 m2 pens on a straw litter at 2 densities (8 or 16 rabbits per m\ in the second experiment, 232 rabbits were housed in the same pens and al the same densities on either straw or wood shavings, while the control group was traditionaliy housed in cages of 2 rabbits. In experiment 1, mortality rate was significantly higher fer rabbits raised on litter al the higher density (15.6% vs 4.2% and 7.5% fer groups housed on litter at low density or in cages, respeclively). Higher death incidence was mainly due to coccidiosis. Thus, a prophylactic treatment was provided to all the animals befere the beginning of experiment 2 resulting in a lack of differences in mortality rate among the groups (9.91 % average). Rabbits housed in cages showed a significantly higher weight gain (41.0 vs 31.7 and 34 g/d) and a better feed efficiency than rabbits housed on litter in experiment 1. On the contrary final live weight, daily weight gain and feed to gain ratio fer caged animals were not significantly higher than fer rabbils housed on litter in experiment 2. However, growth rate of rabbits kept al lower density was significantly higher than fer the other animals reared in pens (33.2 vs 31.0 g/d), while the type of litter had no effects. Caged animals showed a carcass weight and dressing out percentage significantly higher than ali the other groups in the first experiment. Furthermore, the hot carcass weight among rabbils housed on litter was significantly higher fer lower stocking density. In experiment 2, dressing out percentage was significantly better in caged rabbits (57.4%) than in all the other experimental groups (55.1 to 55.8%). Moreover, carcass weight was significantly higher in rabbits kept at lower density than the others ones reared in pens (P<0.05). The full gastrointestinal tract was significantly heavier in rabbits housed in pens on straw litter (22.3% of live weight) in comparison with the caged animals (18,7%). The chemical composition of the caecal content however did not show variation of the gross composition as a function of the litter type. In experiment 1, the meat pH al 45 min and al 24 hrs post mortem, as well as meat colour parameters were the same in all experimental groups. In experiment 2, it can be observed that the hind leg weight was constant among the groups, while the muscle to bone ratio of the cut was significantly higher in caged than in ali the other animals. Furthermore, rabbits on litter had on the whole meat with a higher water and a lower lipid content. In conclusion, group housing systems on litter implies some relevant questions that have to be pointed out, particularly concerning pathology problems (mainly connected to coccidiosis) compared to the intensive breeding in cages. Growth perfermances, slaughter results and carcass quality are on the whole better fer animals traditionaliy raised in wire mesh cages.
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