Butyrate and its derivatives possess various nutritional and biological benefits for mammals, whereas its effects on dairy calves have not been well characterized. This study evaluated the effects of tributyrin administration on blood immune, intestinal immune and barrier functions, and microbial composition of pre-weaned dairy calves. Twenty newborn Holstein bull calves were randomly assigned into a control group (no tributyrin supplementation, CON; n = 10) or a treatment group (supplemented with tributyrin at 2 g/L of milk, TRB; n = 10). The results showed that diarrhea frequency was decreased significantly by tributyrin administration from d 29 to 56 (P < 0.001) and the whole period (P = 0.003, d 1 to 56) though no significant effects were observed on growth performance. For blood metabolites, tributyrin administration significantly reduced the concentration of interleukin-1β (IL-1β) on d 28 (P = 0.001) and tended to reduce the concentration of serum amyloid A on d 56 (P = 0.079), whereas serum oxidative status parameters were not affected. For intestinal development, tributyrin administration increased the villus height (P < 0.001) and the ratio of villus height to crypt depth (P = 0.046) in the jejunum, and the villus height in the ileum (P = 0.074). Furthermore, toll-like receptor 2 (TRL2, P = 0.045) and IL-1β (P = 0.088) gene expressions were downregulated, while Claudin-4 (P = 0.022) gene expression was upregulated in the jejunum following tributyrin administration. In the ileum, Claudin-4 (P = 0.029) and G-protein coupled receptor 41 (P = 0.019) gene expressions were upregulated in the TRB group compared to CON. No significantly higher abundances of microbiota were found in the jejunum or ileum of calves in the CON group. In the TRB group, supplementing tributyrin significantly increased the abundance of short-chain fatty acid (SCFA)-producing bacteria, including Ruminococcaceae, Lachnospiraceae, Prevotella and Rikenellaceae (LDA > 3.5, P < 0.05), which was negatively associated with inflammatory gene expression (TLR2 and IL-1β) but positively associated with intestinal barrier genes (Claudin-4) and morphological parameters (P < 0.05). In conclusion, supplementing tributyrin in milk replacer could improve intestinal development and health of pre-weaned dairy calves by stimulating SCFA-producing bacteria colonization, enhancing intestinal barrier functions and suppressing inflammatory responses.

丁酸盐及其衍生物对哺乳动物具有多种营养和生物学益处，而其对奶牛的影响尚未得到很好的表征。本研究评估了三丁酸甘油酯给药对断奶前小牛的血液免疫、肠道免疫和屏障功能以及微生物组成的影响。将 20 头新生荷斯坦牛犊随机分配到对照组（不补充三丁酸，CON；n = 10）或治疗组（补充 2 g/L 牛奶的三丁酸，TRB；n = 10）。结果表明，在第 29 天至第 56 天（P < 0.001）和整个时期（P= 0.003, d 1 到 56) 虽然没有观察到对生长性能的显着影响。对于血液代谢物，三丁酸甘油酯给药显着降低了第 28 天的白细胞介素 1β ( IL-1β ) 浓度（P = 0.001），并倾向于降低第 56 天血清淀粉样蛋白 A 的浓度（P = 0.079），而血清氧化状态参数不受影响。对于肠道发育，三丁酸甘油酯给药增加了空肠的绒毛高度（P < 0.001）和绒毛高度与隐窝深度的比值（P = 0.046），以及回肠中的绒毛高度（P = 0.074）。此外，toll​​ 样受体 2 ( TRL2 ​​, P = 0.045) 和IL-1β ( P = 0.088) 基因表达下调，而Claudin-4 ( P = 0.022) 基因表达在三丁酸甘油酯给药后在空肠中上调。在回肠中，与 CON 相比，TRB 组Claudin-4 ( P = 0.029) 和 G 蛋白偶联受体 41 ( P = 0.019) 基因表达上调。在 CON 组的小牛的空肠或回肠中没有发现显着更高丰度的微生物群。在 TRB 组中，补充三丁酸可显着增加产生短链脂肪酸 (SCFA) 的细菌的丰度，包括瘤胃球菌科、毛螺菌科、普氏菌属和李氏菌科 (LDA > 3.5,P < 0.05），与炎症基因表达（TLR2和IL-1β）呈负相关，但与肠屏障基因（Claudin-4）和形态学参数呈正相关（P < 0.05）。总之，在代乳粉中补充三丁酸甘油酯可以通过刺激产 SCFA 的细菌定植、增强肠道屏障功能和抑制炎症反应来改善断奶前奶牛的肠道发育和健康。