自拟中草药复方对大肠杆菌攻毒断奶仔猪生长性能、抗氧化能力和免疫功能的影响OA

[Objective]Based on the theory of traditional Chinese veterinary medicine,post-weaning diarrhea caused by eneterotoxigenic Escherichia coli(ETEC)infection in piglets is often associated with the accumulation of"damp-heat"and the susceptibility of spleen and stomach dysfunction during the weaning transition.Therefore,adhering to the therapeutic principle of"clearing heat and invigorating the spleen",this study formulated a herbal compound,"Qingchang San"to evaluate its regulatory effects on growth performance,oxidative stress,and immune response in a piglet model challenged with ETEC.[Method]Fifty-four 23-day-old Duroc×Landrace×Yorkshire(DLY)weaned piglets with similar body weight(7.04 kg±0.37 kg)were randomly divided into three groups:Control group(CON),challenge group(ETEC),and Chinese herbal compound group(ETEC+CH),with 6 replicates per group and 3 piglets per replicate.CON and ETEC group were fed a basal diet(some statistical data were combined into the basic diet group),while ETEC+CH group received the basal diet supplemented with 0.1％"Qingchang San".On day 15,piglets in ETEC and ETEC+CH groups were orally administered 150 mL of ETEC suspension(3×10⁹ CFU/mL)for three consecutive days,whereas piglets in CON group received the same volume of saline.The experiment lasted for 31 days.Growth performance indicators were measured by weighing the piglets on the morning of days 15,18,and 32.Blood samples were collected to separate serum for the determination of serum antioxidant and immune parameters.On day 18,one piglet from each replicate(a total of 18 piglets)was randomly selected and slaughtered,and jejunal mucosa samples were collected for the analysis of immune-related gene expression.[Result]① Results of growth performance and diarrhea indicators showed that in the early stage of infection(15-17 days),compared with CON group,the average daily gain(ADG)of piglets in ETEC group was extremely significantly decreased(P<0.01),while the feed conversion ratio(F/G),diarrhea index,and diarrhea rate were significantly or extremely significantly increased(P<0.05 or P<0.01).Compared with ETEC group,the ADG of piglets in ETEC+CH group showed an increasing trend,and the F/G showed a decreasing trend(0.05≤P<0.10).In the later stage of infection(18-31 days),compared with CON group,the diarrhea rate of piglets in ETEC group increased extremely significantly(P<0.01).Compared with ETEC group,the diarrhea index and diarrhea rate of piglets in ETEC+CH group decreased significantly or extremely significantly(P<0.05 or P<0.01).② Results of serum antioxidant and immune indicators showed that before challenge,compared with basic diet group,total antioxidant capacity(T-AOC),the contents of interleukin-6(IL-6),and immunoglobulin G(IgG)in the serum of piglets in ETEC+CH group were extremely significantly or significantly increased(P<0.01 or P<0.05).On the 18th day,compared with CON group,serum T-AOC and the content of serum IgA in piglets of ETEC group were extremely significantly decreased(P<0.01).Compared with ETEC group,the serum T-AOC in ETEC+CH group was significantly increased(P<0.05),while the contents of serum MDA and IL-6 were significantly or extremely significantly decreased(P<0.05 or P<0.01).By the 32nd day,compared with CON group,the serum T-AOC of piglets in ETEC group was still significantly decreased(P<0.05).③ The gene expression results of jejunal mucosa showed that compared with CON group,the expression of Toll-like receptor 4(TLR4)and its downstream pro-inflammatory factors IL-6,interferon-γ(IFN-γ),IL-1β and IL-18 genes in the jejunal mucosa of piglets in ETEC group increased significantly or extremely significantly(P<0.05 or P<0.01),while the expression of tumor necrosis factor-α(TNF-α)gene was extremely significantly decreased(P<0.01).Compared with ETEC group,the expression of TLR4,myeloid differentiation factor 88(MyD88),tumor necrosis factor receptor-associated factor 6(TRAF6),nuclear transcription factor-κB p65(NF-κB p65)genes,and the above pro-inflammatory factors in the jejunal mucosa of piglets in ETEC+CH group were extremely significantly or significantly decreased(P<0.05 or P<0.01).[Conclusion]ETEC challenge compromised antioxidant and immune homeostasis in piglets,leading to diarrhea and impaired growth performance.Dietary supplementation with"Qingchang San"inhibited the TLR4/NF-κB pathway and the expression of pro-inflammatory cytokines,effectively alleviating ETEC-induced oxidative stress and intestinal inflammation,thereby improving the health status of piglets.These findings provided a scientific basis for the application of"Qingchang San"as an antibiotic alternative in green and healthy swine production.