Effects Of RRR-α-Tocopherol Succinate On Growth Performance, Antioxidant And Immune Function Of Broilers

This study was conducted to study the effects of RRR-α-tocopherol succinate (a-TOS) on growth performance, meat quality, antioxidant and immune function in broilers with all-rac-tocopherol acetate and RRR-α-tocopherol acetate as the comparisons. The object of this study was to supply a laboratory basis for the exploitation of a-TOS in poultry production. The study included four experiments and the results were stated as follows:The first experiment was designed to evaluate the effects of a-TOS with different dose on growth performance, chyme digestive enzyme activity and metabolic rate of nutrients in broilers.600AA broilers were randomly divided into10treatments with6replicates (10birds per replicate), using2x5factorial design:the oil types (fresh and oxidized rancid oil)×a-tocopherol treatments (30mg/kg all-rac-a-tocopherol acetate (TOA1),30mg/kg RRR-a-tocopherol acetate (TOA2),15,30, and60mg/kg TOS (TOS1, TOS2, TOS3), respectively. The experiment lasted for42days. The results showed that (1) Compared with the fresh oil groups, diets with the oxidized rancid oil increased the feed gain ratio (F/G) of broilers at21day of age (P<0.05), decreased the chyme digestive enzyme activity and metabolic rate of nutrients (P>0.05).(2) a-TOS could significantly decreased broilers’F/G (P<0.05) and increase the metabolic utilization of nutrients (P>0.05), it also tended to relieve the degradation of broilers growth performance caused by oxidized rancid oil, and the TOS3group gained the best effectiveness.(3) There was no significant difference among TOA1, TOA2and TOS2groups (P>0.05).The second experiment was conducted to study the effect of a-TOS with different dose on meat quality of broilers, and malondialdehyde (MDA) content, superoxide dismutase (SOD) activity and fluidity of mitochondria membrane were determined to investigate the mechanism. Treatments were the same as the first experment. The results showed (1) Compared with the fresh oil groups, lipid peroxidation of broilers was increased in the oxidized ranced oil treatments, with poorer muscle color and increased drip loss, the fluidity of mitochondria membrane were deceased (P<0.05), and SOD activity of muscles were decreased, the MDA content increased (P>0.05).(2) In both the oxidized rancied and fresh oil treatments, TOS3group could significantly reduce48-h drip loss and cooking loss of muscle (P<0.05), the brightness, the red value and drip loss of thigh in TOS2or TOS3group were improved significantly (P<0.05); The MDA content of thigh muscle in TOS2and TOS3groups were significantly lower (P<0.05or P<0.01). The SOD activity in TOS3group were significantly increased (P<0.05) in comparison with TOS1.(3) There was no significant difference in meat quality among TOA1, TOA2and TOS2groups (P>0.05), but the fluidity of mitochondria membrane of TOA2and TOS2groups were much higher than that of TOA1group.In the third experiment, the effects of a-TOS with different dose on antioxidant of serum and liver of broilers were studied. Treatments were the same as the first experment. The results showed (1) Oxidized rancid oil made the antioxidant capacity of serum decreased to some extent (P<0.05or P<0.01), it also reduced the SOD and GSH-Px activities of liver (P<0.05). The MDA content were significantly increased (P<0.05) in both serum and liver, the VE content and fluidity of mitochondria membrane were also decreased.(2) In both oxidized rancid and fresh oil diets, by the amount of a-TOS increased, the antioxidant capacity of serum and liver were increased to some extent (P>0.05or P<0.05), the MDA levels were significantly reduced (P<0.05), the VE content of serum and liver and fluidity of mitochondria membrane were also increased (P<0.01), and the TOS3group gained the best effectiveness.The effect of a-TOS with different dose on the immune organ development, Newcastle disease antibody titers and cytokines of broilers was studied in the last experiment. Treatments were the same as the first experment. The results showed (1) Compared with the fresh oil groups, diets with the oxidized rancid oil decreased the the immune organ index and Newcastle disease antibody titers (P>0.05), and increased the level of interleukin2(IL-2), interleukin6(IL-6) and tumor necrosis factor a (TNF-a) of broilers (P<0.05or P<0.01).(2) a-TOS could increase the thymus, bursa and spleen indexes (P>0.05) and decrease the level of interleukin2(IL-2), interleukin6(IL-6) and tumor necrosis factor a (TNF-a) of broilers in oxidized rancid oil diets groups (P<0.05).(3) There were no significant differences in immune organ index and Newcastle disease antibody titers among TOA1, TOA2and TOS2groups (P>0.05), but the levels of IL-2, IL-6and TNF-α in TOS2groups were much lower than those of TOA1and TOA2groups.In conclusion, the study showed that oxidized rancid oil could provoke oxidative stress, leading the growth performance of broilers reduced, the meat quality, antioxidant and immune function decreased.30～60mg/kg dietary a-TOS supplementation exerted positive effects on the growth improvement. It could decrease the drip loss and improve the colour to enchance the meat quality. It could also improve the antioxidant capacity, enchance the immune function of broilers by promoting the immune organ development. The main reason might be the increased retention of serum and hepatic a-tocopherol reducing free radical and lipid peroxidation formation, the fluidity of mitochondria membrane increased which be the basic for the normal physiologic function.