Effects Of Xanthophyll On Growth Performance,Antioxidant And Immune Functions Of LPS-Stimulated Yellow-feathered Broilers

This experiment was designed to investigate the effects of xanthophyll on growth performance,antioxidant and immune functions of LPS-stimulated broilers.Experiment 1:This study was designed to establish an immunological stress model of broilers.A total of 140,one-day-old healthy yellow-feathered male broilers were randomly assigned into 2 groups consisting of 7 replicates of 10 chickens each.At day 21,23,25 and 27,chickens were given intraperitoneal injection with 1 mg/kg body weight of LPS in the experimental group,while the control group was injected with the same amount of saline solution.Each group was weighed,and a bird which weight was close to the average weight per group was selected at 24 hours after each injection.Blood samples were taken,and then all chickens were killed,samples were collected.This study lasted for 28 days.The results showed that:Growth performance:After second injection,LPS significantly reduced ADFI,ADG and BWG of broilers(P<0.05).At the same time,LPS significantly increased F/G of broilers in third injection(P<0.05).Antioxidant function:LPS significantly reduced serum SOD activity in first injection(P<0.05).LPS significantly reduced serum CAT activity in second injection(P<0.05).LPS significantly reduced serum,jejunal mucosa and liver SOD,serum and jejunal mucosa CAT,serum,jejunal mucosa and liver GSH-Px activity,jejunal mucosa and liver SOD,CAT and GSH-Px expression and serum and jejunal mucosa GSH/GSSG ratio(P<0.05),as well as increased serum and liver MDA content in third injection(P<0.05).LPS significantly reduced liver SOD,serum and jejunal mucosa CAT,jejunal mucosa and liver GSH-Px activity,jejunal mucosa CAT and GSH-Px expression,and jejunal mucosa GSH/GSSG ratio(P<0.05),as well as increased serum and liver MDA content in fourth injection(P<0.05).Immune function:LPS significantly increased jejunal mucosa IL-6 content in first injection(P<0.05).LPS significantly increased jejunal mucosa and liver IL-1β content in second injection(P<0.05).LPS significantly increased jejunal mucosa and liver IL-1β,jejunal mucosa IL-6,and jejunal mucosa and liver IFN-y content,and jejunal mucosa and liver IL-1β,IL-6 and IFN-y expression(P<0.05),as well as reduced thymus index and bursal index in third injection(P<0.05).LPS significantly increased liver IFN-y content(P<0.05),as well as reduced spleen index in fourth injection(P<0.05).TLR4/MyD88 signaling pathway mRNA expression:LPS significantly increased jejunal mucosa and liver TLR4 and MyD88 expression in third injection(P<0.05).Experiment 2:Based on the results of the first part of the study,this study was designed to investigate the effects of xanthophyll and LPS challenge on growth performance,antioxidant and immune functions of broilers.Meanwhile,the functional mechanism of xanthophyll was studied.2×2 factorial arrangement was used in this study.A total of 240,one-day-old healthy yellow-feathered male broilers were randomly assigned into 4 groups consisting of 6 replicates of 10 chickens each and were fed on a basal diet or 40 mg/kg xanthophyll diet.At day 21,23 and 25,chickens were given intraperitoneal injection with 1 mg/kg body weight of LPS in the experimental group,while the control group was injected with the same amount of saline solution.Each group was weighed,and a bird which weight was close to the average weight per group was selected at 24 hours after last injection.Blood samples were taken,and then all chickens were killed,samples were collected.This study lasted for 26 days.The results showed that:Growth performance:LPS challenge significantly reduced ADFI,ADG and BWG of broilers(P<0.05).Diets supplemented with xanthophyll partly attenuated the decrease of ADG and BWG of broilers(0.05<P<0.1).Antioxidant function:LPS challenge significantly reduced serum,jejunal mucosa and liver SOD,serum and jejunal mucosa CAT,jejunal mucosa and liver GSH-Px activity,liver SOD,jejunal mucosa and liver CAT and GSH-Px expression,and serum and liver GSH/GSSG ratio(P<0.05),as well as increased serum,jejunal mucosa and liver MDA content(P<0.05).In addition,there was a tendency that LPS challenge reduced serum GSH-Px activity and jejunal mucosa SOD expression and GSH/GSSG ratio(0.05<P<0.1).Diets supplemented with xanthophyll significantly increased serum and jejunal mucosa SOD,serum CAT,serum and liver GSH-Px activity,jejunal mucosa CAT and GSH-Px expression,and serum GSH/GSSG ratio(P<0.05),as well as reduced jejunal mucosa MDA content(P<0.05).In addition,jejunal mucosa SOD expression and GSH-Px activity were notable decreased when treated with xanthophyll,while partly attenuated the adverse effects of the treatment of LPS(0.05<P<0.1).Diets supplemented with xanthophyll partly inhibited the increase of serum MDA content(0.05<P<0.1).Immune function:LPS challenge significantly increased jujunal mucosa and liver IL-1β,liver IFN-y content,and jujunal mucosa and liver IL-1β,and jejunal mucosa IL-6 expression(P<0.05).Meanwhile,the increased tendency was seen on jejunal mucosa IL-6 content and liver IL-6 expression(0.05<P<0.1).In addition,LPS challenge significantly reduced thymus index of broliers(P<0.05),and the decreased tendency was seen on spleen index and bursal index(0.05<P<0.1).Diets supplemented with xanthophyll significantly reduced jejunal mucosa and liver IL-1β,jujunal mucosa IL-6 content,and jejunal mucosa and liver IL-1β and IL-6 expression(P<0.05).Meanwhile,thymus index was notable decreased when treated with xanthophyll,while partly attenuated the adverse effects of the treatment of LPS(0.05<P<0.1).TLR4/MyD88 signaling pathway mRNA expression:LPS challenge significantly increased jejunal mucosa and liver TLR4 and MyD88 expression(P<0.05).Diets supplemented with xanthophyll significantly reduced jejunal mucosa TLR4 and MyD88 expression(P<0.05).All in all,three times of 1 mg/kg BW LPS injections established an immunological stress model of broilers.Meanwhile,diets supplemented with xanthophyll obviously attenuated the immune response caused by LPS challenge,improved the antioxidant function and maintained the growth performance in broiler chickens,which may correlate positively with the inhibition of TLR4/MyD88 signaling pathway activation by xanthophyll.