INFLUENCE OF STOCKING DENSITY ON SOME BEHAVIORAL, PHYSIOLOGICAL AND PRODUCTIVITY TRAITS OF BROILERS

In order to investigate the influence of stocking density on broiler w elfare, 17 616 Ross chickens were assigned to three different treatmen ts: T-1, T-2 and T-3 with a final stocking density of 27, 35 and 43 kg /m(2), respectively (corresponding to an initial density of 12, 16 and 20 birds/m(2)). Animal welfare was assessed by measuring behavioural, physiological and productivity traits Behavioural observations includ ed the disturbance frequency of resting birds by other birds, the dura tion of the lying bouts and the standing/lying ratio. The heterophil/l ymphocyte ratios were assessed from blood collected before departure t o the slaughterhouse. Main productivity traits were the final live wei ght and carcass degradation due to foot and pad dermatitis and breast blisters. Most of the observed parameters were adversely affected by t he highest density (P < 0.05). Between T-1 and T-2, some traits tended to demonstrate that a better degree of bird welfare existed in T-1 (h igher standing/lying postures ratio and final live weight, lower frequ ency of pododermatitis and hock lesions; P < 0.05) whereas other trait s showed no differences (frequency of disturbances by other birds duri ng resting, heterophil/lymphocyte ratio). In conclusion, a stocking de nsity of 43 kg/m(2) seemed to induce poor bird welfare whereas it was not clearly demonstrated that 27 kg/m(2) was better than 35 kg/m(2).