Effects And Mechanism Of Compound Immune Stress On Oxidative Damage And Lipid Metabolism In Broilers

This study was to investigate the effects of the immune stress induced by Newcastle Disease ? Series and lipopolysaccharides (LPS) and Anti-stress agent on the growth performance, immune function, antioxidant ability lipid metabolism and mechanism of broilers. The aim of the study was to clarify the mechanism of combined immune stress, to develop a reasonable immunity procedure, to develop Anti-stress agents, and to control the immune stress.Trial 1:The objective of this expriement was to study the effects of compound immune stress on the growth performance, immune function, antioxidant ability lipid metabolism and mechanism of broilers.Methods:128 1d broiler chickens with similar body weight(BW) were randomly divided into 4 groups, A group as control group were injecting and putting drop in noses with normal saline, B group were vaccinated with Newcastle Disease ? Series by putting drop in noses, and C group were vaccinated with Newcastle Disease ? Series by putting drop in noses and injection of low concentration LPS 250?g/kg BW, D group were vaccinated with Newcastle Disease ? Series by putting drop in noses and injection of high concentration LPS 500?g/kg BW.Three test groups were vaccinated with Newcastle Disease ? Series on 15d and 28d.The LPS group was injected with 250?g/kg BW LPS or 500?g/kg BW LPS on 12d,15d,18d and 21d for 4 times. The control group and the experimental group were kept separate from each other. In addition to this, all chickens were not inoculated with other vaccines, the test period was 42 days. After 7,14,21,28day of inoculation, from each group were chosen 8 chicken serum samples were collected to detect immune function, antioxidant ability lipid metabolism and mechanism of broilers. The mRNA expression levels of lipometabolism in liver were analyzed by Real-time-PCR.Results:Compared with the control group, (1) Vaccine immune stress and Compound immune stress significantly reduced 22d broiler weight gain (P<0.01), and weight ratio increased significantly (P<0.05). (2) There was no significant effect on the thymus index of broilers (P>0.05), decreased significantly spleen index and bursal index (P<0.01). (3) The anti oxidative function of broilers was decreased by Compound immune stress. Significantly increased MDA value (P<0.01)and activity of SOD (P<0.01), decreased the activity of GSH-Px (P<0.01). (4) Compound immune stress challenged broilers had lower concentrations of TC (P<0.05), and higher concentrations of TG (P<0.05) and LDL-C (P<0.05). With the increase of day age, there were no differences between the groups (P>0.05). (5)RT-PCR results showed that the mRNA levels of ACC in liver were down-regulated (P<0.01), the mRNA levels of CPT-1?PPAR-? and HMG-COA were up-regulated (P<0.01) by Compound immune stress.Trial 2:The effects of Anti-stress agent on the growth performance, immune function, antioxidant ability lipid metabolism and mechanism of broilers.Methods:A group were vaccinated with Newcastle Disease ? Series by putting drop in noses and injection of low concentration LPS 250?g/kg BW, C group were vaccinated with Newcastle Disease ? Series by putting drop in noses and injection of high concentration LPS 500?g/kg BW. The B, D two groups were treated the same with A, C. The difference is that add 1% Anti-stress agent in the diet.Results:The materials and methods used were the same as those in trial 1. The results showed as follows:(1) The addition of Anti-stress agent in the diet can increase the body weight (P<0.05), reduce the weight ratio (P>0.05), and improve feed conversion efficiency. (2) The addition of Anti-stress agent in the diet to promote the growth and development of immune organs, delay the atrophy of the immune organs (P<0.05), antibody levels also increased (P<0.05). But with the increase of day age, the end of the experiment, there was no significant difference between the compound immune stress and anti-stress agent group (P>0.05). (3) The Anti-stress agent enhanced the antioxidant function of broilers. The MDA content was significantly decreased (P<0.05), and the GSH-Px activity was significantly increased (P<0.01). (4) Anti-stress agent makes the serum TC content decreased (P<0.05), TG content increased (P<0.05), HDL-C content was no significant difference (P>0.05), LDL-C content decreased (P<0.05). (5) Anti-stress agent can significantly improve the mRNA expression of ACC, HMG-COA in the liver (P<0.01), while the CPT-1 activity first decreased and then increased (P<0.01), and decreased the expression of PPAR-? (P<0.01).Conclusion:Compound Immune stress can decrease the broiler growth performance, antioxidant ability and immune function, but on humoral immunity did not significantly influence; it also significantly increased the content of TG and TC in serum of broilers, the mechanism is mainly immune complex stress activates AMPK lipid metabolism pathway, and significantly downregulate the expression of liver ACCmRNA expression and upregulation of CPT-1mRNA, PPAR- ?mRNA and HMG-COAmRNA. The Anti-stress agent was successfully developed, and its effect on growth performance, immune function and antioxidant activity was significantly improved.