This study was aimed to investigate the effects of dietary arctiin (ARC) supplementation (100, 200 and 400 mg/kg) on the growth performance and immune response of broilers after a Salmonella pullorum (S. pullorum) challenge, and we conducted in vitro anti-bacterial test to explore the bacteriostatic mechanism of ARC. The in vivo trial was randomly assigned to 6 groups: non-infected control group (NC) and positive control group (PC) received a basal diet; TET group, received a basal diet supplemented with 100 mg/kg chlortetracycline; ARC100, ARC200 and ARC400 groups received a basal diet containing 100, 200, 400 mg/kg ARC, respectively. From d 14 to d 16, all birds (except NC group) were infected with 1 mL (1×10 8 CFU/mL) fresh S. pullorum culture by oral gavage per day. In vivo results showed that dietary supplementation of 200 mg/kg ARC significantly increased average daily gain (P<0.05) and decreased feed-to-gain ratio of broilers versus the PC group during d 15-28 after challenged with S. pullorum (P<0.05). The jejunal crypt depth (CD) were decreased by supplementing 100 or 200 mg/kg ARC in diets compared with PC birds at d 19 (P<0.05). The jejunal villi height (VH) were increased by supplementing 100, 200 or 400 mg/kg ARC in diets compared with PC birds at d 28 (P<0.05). Besides, dietary supplementation of 200 mg/kg ARC increased the jejunal VH to CD ratio (VH:CD) than PC group both at d 19 and d 28 (P<0.05). Notably, the broilers had lower serum lipopolysaccharide (LPS) and diamine oxidase (DAO) levels in the ARC100 and ARC200 groups at d 28 than those in the PC group (P<0.05). Furthermore, in comparison to PC birds, the birds in ARC groups (100, 200, 400 mg/kg) had higher serum contents of IgM and IL-10, and the birds in ARC200 group had higher serum contents of IgA at d 19 (P<0.05). At d 28, the birds in ARC groups (100, 200, 400 mg/kg) had lower serum contents of IL-8, and the birds in ARC200 group had lower serum contents of IFN-γ compared to the PC birds (P<0.05). The in vitro experiment showed that ARC significantly inhibited the biofilm formation and adhesion of S. pullorum (P<0.05). Metabonomics analysis revealed that ARC can restrain the formation of the biofilm by affecting a variety of metabolic pathways of S. pullorum. Therefore, dietary supplementation of 200 mg/kg ARC might be a potentially way to substitute antibiotics to control S. pullorum infection in broilers.

中文翻译：

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牛蒡子苷对白痢沙门氏菌感染肉鸡的保护作用及可能机制

本研究旨在探讨日粮中添加牛蒡苷 (ARC)（100、200 和 400 mg/kg）对鸡白痢沙门氏菌（S. pullorum）攻击后肉鸡生长性能和免疫反应的影响，我们在体外进行了抗菌试验探讨ARC的抑菌机制。体内试验随机分为6组：未感染对照组（NC）和阳性对照组（PC）接受基础饮食；TET组，基础饮食中添加100 mg/kg金霉素；ARC100、ARC200和ARC400组分别接受含有100、200、400 mg/kg ARC的基础饮食。第14天至第16天，所有鸡（NC组除外）每天经口灌胃感染1mL（1×10 8 CFU/mL）新鲜鸡白痢。体内结果表明，日粮中添加 200 mg/kg ARC 显着增加肉鸡的平均日增重（P<0.05），并在白痢沙门氏菌攻击后第 15-28 天期间，与 PC 组相比，降低肉鸡的料增比（P<0.05）。 ；0.05)。与PC鸡相比，第19天时，通过在日粮中添加100或200 mg/kg ARC，空肠隐窝深度（CD）降低（P＜0.05）。与PC鸡相比，第28天时，通过在日粮中添加100、200或400mg/kg ARC，空肠绒毛高度(VH)增加(P＜0.05)。此外，膳食补充200 mg/kg ARC在第19天和第28天均比PC组增加了空肠VH与CD比率(VH:CD)(P<0.05)。值得注意的是，第28天时ARC100和ARC200组肉鸡的血清脂多糖（LPS）和二胺氧化酶（DAO）水平低于PC组（P＜0.05）。此外，与PC鸡相比，ARC组（100、200、400mg/kg）的鸡在第19天时具有更高的血清IgM和IL-10含量，并且ARC200组的鸡在第19天时具有更高的血清IgA含量（ P＜0.05)。第28天，ARC组（100、200、400mg/kg）血清IL-8含量低于PC组，ARC200组血清IFN-γ含量低于PC组（P＜0.05）。 0.05）。体外实验表明，ARC显着抑制白痢沙门氏菌生物膜形成和粘附（P<0.05）。代谢组学分析表明，ARC可以通过影响白痢沙门氏菌的多种代谢途径来抑制生物膜的形成。因此，日粮中添加 200 mg/kg ARC 可能是替代抗生素控制肉鸡白痢沙门氏菌感染的潜在方法。