Effect Of Stress On Lipid Peroxidation And Meat Quality Of Broilers

Two experiments were conducted in the present study to determine the effects of acute stress and chronic stress on lipid peroxidation and meat quality of broilers by exogenous glucocorticoids.In exp.1, broilers were injected with corticosteron to induce stress, to determine the effect of acute stress on lipid peroxidation and meat quality of broilers. At 42d of age ,2 groups of 12 AA broiler chickens were used and injected subcutaneously with corticosterone(4 mg/kg BW)or corn oil(as sham control). A blood sample was respectively obtained before and 3 h after CORT or oil administration. After obtaining the breast muscle samples from these living chickens, they were killed after cutting the jugular vein. The breast and thigh muscle were taken at 0h postmortem and the eviscerated carcasses were chilled for 24h or 48h at 4°C. Following the 24 h or 48h storage,the breast and thigh muscle samples were respectively cut again and the underlying biochemical changes were analysed. The results indicated that acute stress decreased the Bw of birds sharply, the content of plasma glucose, uric acid, T-AOC, MDA were signicantly higher than the control group, the content of MDA in BM and T-AOC in PM were increased, the buffering capacity and content of glycogen in living PM were also increased, the pH of preslaughter PM was declined, but the cooking loss of the stressed group was not increased significantly, and drip loss trended to be lower.In exp.2, broilers fed with diets of different VE level were injected with dexamethasone to induce chronic stress, to investigate the effect of chronic stress and VE level on lipid peroxidation and meat quality. 140 male broilers of 1d were divided into two different feed groups (200mg VE/kg diet and 20mg VE/kg diet). At the day of 35, 10 chickens from each group were killed after cutting the jugular vein, then samples were pbtained as basic level group.And the rest were divided into control group, pair-fed group and chronic stress group. Chronic stress group were injected with dexamethasone(2 mg/kg), control group and pair-fed group were injected with sult, and the intake of pair-fed group were consistent with the feed intake of stress group of last day during 6 continual days. At the day of 38 and 41, samples were obtained from each group. The results indicated that the performance of birds suffered from chronic stress were significantly lower, the immune organs index declined while liver index and heart index rised, T-AOC and content of MDA in plasma and thymus, SOD activity in muscle were increased, C18:2, PUFA and PUFA/SFA were decreased, drip loss and cooking loss of the stressed group were increased. VE supplement improved the performance, decreased content of MDA in plasma and thymus and SOD activity in muscle, added to the VE level in PM, however, not improved the meat quality and the composition of fatty acid which were influenced by stress.