Effects Of Compound Acidifier Or/and Radix Bupleurum Extract On Growth Performance And Immune Function Of Broilers Challenged With Coccidia

This study included two experiments.The aim of experiment 1?Exp1?was to determine the effect of compound acidifier addition on the performance and immune function of the starter broilers challenged with coccidian vaccine,and to find the suitable added level of acidifier in starter broiler diet.The object of Exp2 was to determine the effects of suitable level of compound acidifier identified in Exp1 alone or combination with and Radix Bupleuri extract on the performance,duodenal morphology,and immune function in the starter broilers challenged with Eimeria acervulina.Exp1.effects of compound acidifier on the performance and immune function of starter broilers challenged with coccidian vaccineA total of 420 1-d-old male broilers?ROSS 308?were randomly allotted into five groups with 7 replicate cages each?12 bird per replicate?.Five dietary treatments included the basal diet without vaccine inoculation?PC?,the basal diet+vaccine inoculation?NC?,the basal diet supplemented with 0.1%acidifier+vaccine inoculation?NCA0.1%?,the basal diet supplemented with 0.2%acidifier+vaccine inoculation?NCA0.2%?,and the basal diet supplemented with 200 mg diclazuril/kg?NCD?.The compound acidifier is the complex of lactic acid,fumaric acid,and citric acid.On d 15,each bird from vaccine-inoculated groups was orally inoculated with attenuated coccidian vaccine?containing 2.2×10⁴ oocysts of Eimeria acervulina,Eimeria tenella Eimeria maxima,and Eimeria necatrix complex?.On d21,one bird from each replicate was selected to collect the blood,spleen,and jejunum for analyses.The results were as following:1)as compared to PC group,the body weight?BW?of 21-d broilers,and body weight gain?BWG?during d 15 to 21 were lower?P<0.01?in NC and NCA0.2%groups,and no significant difference was observed among other group;2)serum uric acid concentration was higher?P<0.01?and serum high-density lipoprotein?HDL?concentration was lower?P<0.05?in NC,NCA0.1%and NCA0.2%groups than in PC group;3)the concentrations of serum interleukin?IL?2 and nitric oxide?NO?were higher?P<0.001?in NC group than in PC group;however,addition of acidifier decreased?P<0.05?the concentrations of serum IL-2 and NO in NCA0.1%and NCA0.2%groups as compared to NC group;4)when compared to PC group,the mRNA abundance of spleen IL-2 in NC,NCA0.2%,and NCD groups and spleen IL-6 in NCA0.2%group increased?P<0.01?,but spleen IL-10 mRNA level in NCA0.1%group decreased?P<0.05?;5)the vaccine inoculation decreased the mRNA abundance of jejunal zonula occudens-2?ZO-2?and mucin 2?MUC2?;the jejunal occludin?OCLN?mRNA level was higher in NC and NCA0.2%groups than PC group.The results suggested that the addition of 0.1%compound acidifier could alleviate the negative effect of coccidian vaccine on the performance of starter broilers.Exp2:effects of compound acidifier and Radix Bupleuri extract alone or combination on the performance and immune function of broilers challenged with Eimeria acervulinaA total of 480 1-d-old broilers?ROSS 308?were randomly divided into five treatments with 6 replicate cage each?8 male and 8 female birds per replicate?.Five treatments included the basal diet without E.acervilina inoculation?PC?,the basal diet+E.acervilina inoculation?NC?,the basal diet supplemented with 0.1%acidifer+E.acervilina inoculation?NCA?,the basal diet supplemented with 0.1%Radix Bupleuri extract+E.acervilina inoculation group?NCB?,and the basal diet supplemented with 0.1%acidifer and 0.1%Radix Bupleuri extract+E.acervilina inoculation?NCAB?.On d 15,each bird from vaccine-inoculated groups was orally inoculated with attenuated coccidian vaccine?containing 7.8×10⁴ oocysts of Eimeria acervulina?.On d 21,one bird from each replicate was selected to collect the blood,spleen,and jejunum for analyses.The results were as following:1)the compound acidifier addition increased the BW on d 14,and BWG during d 1 to 14,and the BWG was higher in NCA and NCAB groups than in NC group during d 15 to 21;2)the number of fecal oocysts was lower in NCB group than in NC group on 5 days post-inoculation,and it was lower in NCAB group than in NC group on 5 and 7 days post-inoculation;3)when compared to NC group,the percentage of CD³⁺CD⁴⁺lymphocytes in the blood increased in NC,NCA,and NCAB groups;the percentages of CD³⁺CD⁴⁺and CD³⁺CD⁸⁺lymphocytes in the blood were lower in NCB group than in NC group;4)E.acervulina inoculation increased the concentration of serum IL-1?and IFN-?and iNOS activity,whereas addition of acidifier and plant extract decreased these three indices;5)the mRNA abundance of spleen IL-6 in NCB and NCAB groups and spleen IL-2 mRNA level in NCAB group were higher than in PC group;6)the crypt depth was higher in NCA,NCB,and NCAB group than in NC group;7)the mRNA abundance of duodenal CLDN1 and MUC2 were lower in the acidifier treated groups than NC group,and plant extract decreased duodenal MUC2 mRNA expression when compared to NC group.These results suggested that the 0.1%compound acidifier or/and 0.1%Radix Bupleuri extract alleviated the negative effects of Eimeria acervulina challenge on the performance of the starter broilers,whereas there was no additive effect of these two supplements.In summary,the addition of 0.1%compound acidifier could alleviated the negative effect of coccidian inoculation on the performance of the starter broilers,which might related to the improvement of inflammation responses and intestinal morphology.