Butyrate promotes the growth and gastrointestinal development of calves. But, the mechanisms behind its effects on signaling pathways of the gastrointestinal tract and rumen microbiome is unclear. This study aimed to reveal transcriptomic pathways of gastrointestinal epithelium and microbial community in response to butyrate supplementation in calves fed a high fiber starter. Fourteen Holstein bull calves (39.9 ± 3.7 kg, 14 d of age) were assigned to 2 groups (sodium butyrate group, SB; control group, Ctrl). The SB group received 0.5% SB supplementation. At d 51, the calves were slaughtered to obtain samples for analysis of the transcriptome of the rumen and jejunum epithelium as well as ruminal microbial metagenome. Sodium butyrate supplementation resulted in a higher performance in average daily gain and development of jejunum and rumen papillae. In both the rumen and jejunum epithelium, SB down-regulated pathways related to inflammation including NF-κB (PPKCB, CXCL8, CXCL12), interleukin-17 (IL17A, IL17B, MMP9), and chemokine (CXCL12, CCL4, CCL8) and up-regulated immune pathways including the intestinal immune network for immunoglobulin A (IgA) production (CD28). Meanwhile, in the jejunum epithelium, SB regulated pathways related to nutritional metabolism including nitrogen metabolism (CA1, CA2, CA3), synthesis and degradation of ketone bodies (HMGCS2, BDH1, LOC100295719), fat digestion and absorption (PLA2G2F, APOA1, APOA4), and the PPAR signaling pathway (FABP4, FABP6, CYP4A11). The metagenome showed that SB greatly increased the relative abundance of Bacillus subtilis and Eubacterium limosum, activated ruminal microbial carbohydrate metabolism pathways and increased the abundance of carbohydrate hydrolysis enzymes. In conclusion, butyrate exhibited promoting effects on growth and gastrointestinal development by inhibiting inflammation, enhancing immunity and energy harvesting, and activating microbial carbohydrate metabolism. These findings provide new insights into the potential mechanisms behind the beneficial effects of butyrate in calf nutrition.

丁酸盐促进犊牛的生长和胃肠道发育。但是，其对胃肠道和瘤胃微生物组信号通路影响的机制尚不清楚。本研究旨在揭示饲喂高纤维发酵剂的犊牛中胃肠道上皮和微生物​​群落对丁酸盐补充的反应的转录组学途径。将 14 头荷斯坦小牛（39.9 ± 3.7 kg，14 天龄）分配至 2 组（丁酸钠组，SB；对照组，Ctrl）。SB组补充0.5%的SB。第51天，宰杀犊牛以获得样品用于分析瘤胃和空肠上皮的转录组以及瘤胃微生物宏基因组。补充丁酸钠可以提高平均日增重以及空肠和瘤胃乳头的发育。PPKCB、CXCL8、CXCL12）、白细胞介素 17（IL17A、IL17B、MMP9）和趋化因子（CXCL12、CCL4、CCL8）以及上调的免疫通路，包括用于产生免疫球蛋白 A (IgA) 的肠道免疫网络 ( CD28 )。同时，在空肠上皮中，SB调节与营养代谢相关的途径，包括氮代谢（CA1、CA2、CA3）、酮体的合成和降解（HMGCS2、BDH1、LOC100295719）、脂肪消化和吸收（PLA2G2F、APOA1、APOA4）和 PPAR 信号通路（FABP4、FABP6、CYP4A11）。宏基因组显示 SB 大大增加了枯草芽孢杆菌和利莫苏真杆菌激活瘤胃微生物碳水化合物代谢途径并增加碳水化合物水解酶的丰度。总之，丁酸盐通过抑制炎症、增强免疫力和能量收集以及激活微生物碳水化合物代谢而表现出对生长和胃肠道发育的促进作用。这些发现为丁酸盐对犊牛营养有益作用背后的潜在机制提供了新的见解。