Effects Of Different Selenium Sources And Levels In Ration On The Antioxidant Capacity And Meat Quality Of AA Broilers

The study was conducted to investigate the effects of different selenium sources and levels in ration on the growth performance, the antioxidant capacity, the Se distribution and the meat quality of Arbor Acres (AA) broilers in order to reveal the effectiveness and the bioavailability of selenium yeast relative to Na2SeO3in broiler chickens. The results will provide the scientific basis for a reasonable choice between different selenium sources of feed in poultry production. This study included three experiments:In trial1, the effects of different selenium sources and its different levels in ration on the growth performance, the Se distribution and the antioxidant capacity in broilers were studied. It has also worked out on feasibility of using0.2mg/kg organic Se replacing0.3mg/kg inorganic Se in the production. Six hundred1-day-old Arbor Acres broiler chickens were randomly assigned into five experimental groups. Control group fed a diet without Se supplementation or experimental diets supplemented with:0.3mg/kg sodium selenite (SS);0.2mg/kg Se-yeast (SYI);0.3mg/kg Se-yeast (SYⅡ) and0.3mg/kg mixed Se (0.15mg/kg SS+0.15mg/kg SY)(MS). The trial was conducted for two periods:the starter (1-21d) and the finishing period (22-42d). The results showed that, the treatments which added organic selenium decreased the ADFI of the starter and whole period of broilers significantly (P<0.05or P<0.01), but it didn’t affect BWG or F/G of growth performance (P>0.05). The groups added organic selenium increased tissue Se concentrations significantly (P<0.05or P<0.01) compared with control and SS groups. In the starter period, the SS, SYI and SYII group increased the hepatic T-SOD activity significantly (P<0.05or P<0.01) compared with control group; the MDA concentration of breast muscles in SYI group and of thigh muscle in all treatments were significantly lower (P<0.05or P<0.01) compared with the control group; the SYI and MS groups increased the T-AOC in thigh muscle significantly (P<0.05) compared with SS group; and the SYII group increased the GSH-Px activity in plasma, the T-SOD activities in plasma and breast muscle as well as the CAT activity in breast muscle significantly (P<0.05) compared with the control and SS groups. In the finishing period, SS, SYI and SYII groups increased the GSH-Px activities in plasma and liver significantly (P<0.05or P<0.01) compared with the control group; SYII group increased the T-SOD and T-AOC activities in breast muscle significantly (P<0.05or P<0.01) compared with the control group; MS group increased the CAT activity in liver significantly (P<0.05or P<0.01) compared with the control group; and the level of plasma MDA in the groups added organic Se was significantly lower (P<0.05or P<0.01) compared with all experimental groups.In trial2, the effects of different selenium sources and its different levels in ration on the meat quality in broilers were studied. The treatments were the same as that of trial1. The trial was conducted for42d. The results showed that, comparing with control group, the SS group increased the cooking loss of thigh muscles significantly (P<0.05); the SYI group increased the pH24value of breast and thigh muscles as well as the pressure loss of thigh muscles significantly (P<0.05); the SYII and MS groups increased the lightness of breast muscles significantly (P<0.05); and the MS group increased the drip loss at24hour post-mortem and cooking loss of thigh muscles significantly (P<0.05). Comparing with control group, the MS group decreased the drip loss at48hour post-mortem of breast muscles and the shear force of thigh muscles significantly (P<0.05). Comparing with SS group, the SYI group increased the pH24value of breast muscles significantly (P<0.05); the SYII group increased the drip loss at48hour post-mortem of thigh muscles significantly (P<0.05); and the MS group increased the drip loss at24or48hour post-mortem of thigh muscles significantly (P<0.05or P<0.01). Comparing with SS group, the SYI group decreased the cooking loss of breast muscles and shear force of thigh muscles significantly (P<0.05); the SYII group decreased the pressure loss of thigh muscles significantly (PV.05), and the MS group decreased the48hour post-mortem of breast muscles and shear force of thigh muscles significantly (P<0.05).In term of chemical composition of muscles, comparing with the control group, the crude fat content of breast muscles in SS and SYI groups as well as the moisture of thigh muscles in SYI group increased significantly (P<0.05or P<0.01); the crude fat content of thigh muscles in SYII and MS groups were significantly lower (P<0.05or P<0.01); the moisture of breast muscles in MS group and the crude ash content of breast muscles in the three groups (SS, SYI and SYII) decreased significantly (P<0.05or P<0.01). Moreover, the groups added organic selenium increased tissue Se concentrations significantly (P<0.01) compared with control and SS groups; SYI and SYII groups decreased the level of MDA of breast muscles significantly (P<0.01) compared with control and SS groups (P<0.05).In trial3, the effects of different selenium sources in ration on antioxidant capacity of stressed broilers were studied. A2×3factorial arrangement of treatments was used in which Se (basal diet,0.3mg/kg sodium selenite or0.3mg/kg selenium yeast) and LPS challenge were the factors. Half birds from each treatment were challenged with0.9%NaCl solution or LPS (250μg/kg body weight) intraperitoneally in the lower abdominal region at16,18and20d of age. The results showed that, injection of LPS significantly decreased the selenium concentration in liver, the T-SOD activity in plasma and liver, the GSH-Px activity in liver and thigh muscle as well as the T-AOC in liver and muscles (P<0.05or P<0.01). While, injection of LPS significantly increased the selenium concentration of breast muscles, all tissue MDA levels and the GSH-Px activity in breast muscle (P<0.05or P<0.01). Supplementation of selenium increased the selenium concentration of plasma and muscles, the T-SOD activity in plasma and breast muscle, the GSH-Px activity in plasma, the CAT activity in breast and thigh muscles significantly (P<0.05or P<0.01). Supplementation of selenium decreased the level of MDA of thigh muscle significantly (P<0.01). Furthermore, organic Se is more effective than inorganic Se.In conclusion, by increasing tissue Se distribution, the improvement in growth performance and antioxidant capacity of the selenium yeast was more effective than sodium selenite as Se supplemented in ration. Furthermore, Se supplementation was more efficient in poultry production of stress status, and0.3mg/kg organic selenium had the best effects. Organic selenium was also more effective on enhancing meat quality and chemical composition of muscles which0.3mg/kg mixed selenium had the best effects.