Previous research has shown that dietary supplementation of Bacillus spp. probiotics exerts beneficial effects on animals’ growth. However, limited studies have evaluated the efficacy of Bacillus spp. on weaned pigs and their effects on host gut health and microbiome, and systemic immunity using a disease challenge model. The objective of this experiment was to investigate the effects of two Bacillus spp. strains (Bacillus subtilis DSM 32540 and Bacillus pumilus DSM 32539) on growth performance, diarrhea, intestinal health, microbiome, and systemic immunity of weaned pigs experimentally infected with an enterotoxigenic Escherichia coli (ETEC). Pigs in PRO1 (Bacillus subtilis DSM 32540) had greater (P < 0.05) body weight on d 7 and 14 PI, greater (P < 0.05) ADG from d 0 to 7 and d 7 to 14 PI, compared with pigs in CON (Control). Pigs in PRO1 had milder (P < 0.05) diarrhea on d 2 and 3 PI compared with pigs in CON. However, no differences were observed in growth performance and diarrhea score between PRO2 (Bacillus pumilus DSM 32539) and CON groups. Supplementation of PRO1 decreased (P < 0.05) lymphocyte counts on d 7 and 14 PI, compared with CON. Supplementation of PRO1 and PRO2 both reduced (P < 0.05) total coliforms in mesenteric lymph nodes on d 21 PI. Pigs in PRO2 had greater (P < 0.05) goblet cell number and sulfomucin percentage in duodenal villi and greater (P < 0.05) sialomucin percentage in jejunal villi than pigs in CON. Supplementation of PRO1 up-regulated (P < 0.05) MUC2 gene expression in jejunal mucosa and reduced (P < 0.05) PTGS-2 and IL1B gene expression in ileal mucosa on d 21 PI, compared with CON. Pigs in PRO1 had reduced (P < 0.05) relative abundance of families Lachnospiraceae, Peptostreptococcaceae and Pasteurellaceae in the ileum. Supplementation of Bacillus subtilis DSM 32540 improved growth performance, alleviated diarrhea severity, enhanced gut health, and reduced systemic inflammation of weaned pigs infected with ETEC F18. Although Bacillus pumilus DSM 32539 was able to alleviate systemic inflammation, it had limited impacts on growth performance and severity of diarrhea of ETEC F18 challenged weaned pigs.

中文翻译：

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膳食芽孢杆菌属 通过调节肠道菌群和全身免疫增强断奶仔猪的生长和抗病能力。

以前的研究表明，膳食补充芽孢杆菌属。益生菌对动物的生长产生有益的影响。然而，有限的研究评估了芽孢杆菌属的功效。使用疾病挑战模型研究断奶猪及其对宿主肠道健康和微生物组以及全身免疫的影响。本实验的目的是研究两种芽孢杆菌的影响。菌株（枯草芽孢杆菌 DSM 32540 和短小芽孢杆菌 DSM 32539）对实验性感染产肠毒素大肠杆菌 (ETEC) 的断奶仔猪的生长性能、腹泻、肠道健康、微生物组和全身免疫力的影响。与 CON 中的猪相比，PRO1（枯草芽孢杆菌 DSM 32540）中的猪在第 7 天和第 14 天的体重更大（P < 0.05），在第 0 至 7 天和第 7 至 14 天的平均日增重更高（P < 0.05）（控制）。与 CON 中的猪相比，PRO1 中的猪在第 2 天和第 3 天 PI 的腹泻较轻 (P < 0.05)。然而，PRO2（短小芽孢杆菌 DSM 32539）和 CON 组之间的生长性能和腹泻评分没有观察到差异。与 CON 相比，PRO1 的补充降低了（P < 0.05）第 7 天和第 14 天 PI 的淋巴细胞计数。补充 PRO1 和 PRO2 在 PI 后第 21 天都减少了 (P < 0.05) 肠系膜淋巴结中的总大肠菌群。PRO2 组猪的十二指肠绒毛杯状细胞数和磺胺粘蛋白百分比更高（P < 0.05），空肠绒毛中唾液酸粘蛋白百分比高于 CON 组猪（P < 0.05）。与 CON 相比，补充 PRO1 上调（P < 0.05）空肠粘膜中的 MUC2 基因表达，并在 21 天后降低（P < 0.05）回肠粘膜中的 PTGS-2 和 IL1B 基因表达。PRO1 中的猪减少了（P < 0. 05)回肠中毛螺菌科、消化链球菌科和巴斯德菌科的相对丰度。补充枯草芽孢杆菌 DSM 32540 可改善感染 ETEC F18 的断奶仔猪的生长性能、减轻腹泻严重程度、增强肠道健康并减少全身炎症。虽然短小芽孢杆菌 DSM 32539 能够缓解全身炎症，但它对 ETEC F18 攻击断奶仔猪的生长性能和腹泻严重程度的影响有限。