亚急性瘤胃酸中毒（SARA）不利于瘤胃发酵及健康。团队研究发现，提高饲粮瘤胃降解淀粉（RDS）影响瘤胃微生物区系而导致奶山羊SARA，饲喂相同高RDS饲粮不同奶山羊SARA发生风险不同。本项目假设低SARA风险奶山羊瘤胃上皮外泌体miRNA可调控瘤胃微生物区系，稳定瘤胃pH，减少炎症反应。本项目拟通过逐步增加小麦替代玉米比例构建高RDS饲粮并筛选高低SARA风险奶山羊，结合上皮转录组及瘤胃细菌16SrRNA基因测序，筛选出调控SARA发生的差异菌群。运用外泌体miRNA测序分析瘤胃上皮及瘤胃内容物中的共差异miRNA，结合差异菌群筛选宿主调控瘤胃微生物区系的潜在miRNA。运用瘤胃菌群移植、人工外泌体miRNA制备及无菌小鼠平台，验证miRNA对关键细菌定植及菌群改变后对SARA的调控作用。预期结果可阐明奶山羊瘤胃上皮外泌体miRNA调控SARA发生的宿主-微生物互作机制。

Excessively fermentable diets can reduce ruminal pH and increased the risk of subacute ruminal acidosis (SARA), which affects rumen function and health. Our previous studies have proved that the increase of rumen degradable starch (RDS) could significantly change the rumen fermentation, PH, and further induce the inflammatory response. Meanwhile, we also found that the dairy goats could have different subacute ruminal acidosis risk with the same RDS feeds. We assume that the dairy goats with a lower or greater subacute ruminal acidosis risk shape the ruminal microbiota via the rumen epithelium secreted exosome microRNA. The present study aims to select out the dairy goats with a lower or greater subacute ruminal acidosis risk by using the diet with high RDS. Then the key microbes which are related to the rumen fermentation, PH, and the inflammatory response of goat during SARA will be selected out by using the 16SrRNA gene sequencing and the mRNA sequencing. Following, the co-differential miRNAs from rumen epithelium which could regulate the rumen microbiota were screened out by using miRNA sequencing. At last, the rumen microbiome transplantation, the preparation of artificial exosome miRNA, and the germ-free mice were used to test the role of miRNAs in regulating the rumen microbiota and the role of key rumen microbes in regulating rumen fermentation, PH, and the inflammatory response of goat during SARA. Our results could illuminate the relationship among RDS, microbes, and host during the generating process of SARA.