Effects Of Rare Earth-chitosan Chelate On Immune And Antioxidative Function Of Broilers

This experiment was conducted to investigate the effects of different doses of rare earth-chitosan chelate(RECC)on growth performance,immune and antioxidant indices in liver,spleen and small intestine tissue samples of broilers,and to explore preliminarily the regulatory mechanism of RECC on immune and antioxidant functions of broilers.A total of 192 one-day-old Arbor Acres(AA)broilers were randomly divided into 4 diet groups with 6 replicates per treatment and 8 broilers per replicate(male and female half)using a single-factor randomized block design.There was no significant difference in initial body weight between groups.The control group was fed a basal diet,and the three experimental groups were fed the basal diet supplemented with 150,200 and 250 mg/kg RECC,respectively.The experiment lasted for 42 days,from d 1 to 21 in the early stage and from d 22 to 42 in the late stage.(1)The effects of RECC on growth performance of broilers were investigated by recording the initial weight,final body weight,feed intake and surplus feed at different stages,and the average daily gain(ADG),average daily feed intake(ADFI)and feed to gain ratio(F/G)were calculated.The results showed that RECC supplementation increased ADG and decreased F/G of broilers,suggesting that RECC can improve feed conversion rate of broilers and promote economic benefit of managers.The growth performance of broilers was significantly improved when the dosage was 175-200 mg/kg.(2)To investigate the effects of RECC on immune function of broilers and its mechanism,the contents of cytokines and immunoglobulins and the expression levels of TLR4/NF-κB signaling pathway related genes in liver,spleen and small intestine tissue samples were determined.The results showed that RECC supplementation increased the contents of IL-2,IL-4,Ig A,s Ig A,Ig G and Ig M,and decreased the contents of IL-1β and IL-6 in liver,spleen and intestine tissues of broilers to varying degrees.Meanwhile,RECC inhibited the expression of genes related to TLR4/NF-κB signaling pathway,and inhibited the gene expression of TLR4,My D88,NF-κB p50,NF-κB p65 and IL-6 m RNA,thereby reducing the release of inflammatory factors.(3)The effects of RECC on antioxidant function of broilers and its mechanism were investigated by measuring the activity or content of antioxidant indexes in liver,spleen and intestine tissue samples and the expression level of Nrf2 signaling pathway related genes in tissue samples.The results showed that RECC increased the activities of T-AOC,GSH-Px,CAT and SOD in liver,spleen and small intestine of broilers,and decreased the content of MDA,and the antioxidant enzyme activities showed a "low promoting and high inhibiting" effect with the increase of dose.At the same time,RECC can activate the Nrf2 signaling pathway and enhance the m RNA expressions of Nrf2,CAT,GPx-7 and SOD in the pathway to regulate the antioxidant function of the body.In conclusion,RECC supplementation can improve the growth performance of broilers.The immune function was regulated by inhibiting the expression of related factors in TLR4/ NF-κB signaling pathway and reducing the release of inflammatory factors.The antioxidant function can be regulated by activating Nrf2 signaling pathway related factors and enhancing antioxidant enzyme activity.In this study,the addition of 175-200 mg/kg RECC in broiler diets significantly promoted growth.