This study was conducted to investigate the effects of combined supplementation of sodium humate (HNa) and glutamine (Gln) on growth performance, diarrhea incidence, serum parameters, intestinal microbiome, and metabolites of weaned calves. In Exp. 1, 40 calves were randomly assigned to four treatments: 1) NC (negative control, basal diet), 2) 1% H+1% G (basal diet extra orally gavaged with 1 g of HNa and 1 g of Gln daily), 3) 3% H+1% G (basal diet extra orally gavaged with 3 g of HNa and 1 g of Gln daily), and 4) 5% H+1% G (basal diet extra orally gavaged with 5 g of HNa and 1 g of Gln daily). The HNa and Gln were together mixed with 100 mL of milk replacer (51 to 58 d of age) or water (59 to 72 d of age) and orally administrated to each calf from a bottle before morning feeding. In a 21-d trial, calves on the 5% HNa+1% Gln group had higher (P < 0.05) average daily gain (ADG) and lower (P < 0.05) diarrhea incidence than those in the control group. In Exp. 2, 20 calves were randomly assigned to two treatments fed with a basal diet and a basal diet supplemented with 100 mL of 5% HNa+1% Gln. In a 21-d trial, calves supplemented with HNa and Gln had higher (P < 0.05) ADG, IgG concentration and glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) activities in the serum, but lower (P < 0.05) diarrhea incidence, as well as serum diamine oxidase (DAO), D-isomer of lactic acid (D-lac), tumor necrosis factor-α (TNF-α), and malondialdehyde (MDA) concentrations compared with control group. Results of intestinal microbiota indicated that supplementation with HNa and Gln significantly increased (P < 0.05) the abundance of intestinal beneficial microbiota. Moreover, supplementation with HNa and Gln altered 18 metabolites and enriched 6 Kyoto Encyclopedia of Genes and Genomes pathways in weaned calves. In conclusion, combined supplementation with HNa and Gln could decrease diarrhea incidence of weaned calves via altering intestinal microbial ecology and metabolism profile.

中文翻译：

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通过肠道微生物群和代谢物的变化，联合补充腐植酸钠和谷氨酰胺可降低断奶犊牛腹泻的发生率

本研究旨在调查联合补充腐植酸钠 (HNa) 和谷氨酰胺 (Gln) 对断奶小牛的生长性能、腹泻发生率、血清参数、肠道微生物群和代谢物的影响。在 Exp。1、40 头小牛被随机分配到四个处理组：1) NC（阴性对照，基础日粮），2) 1% H+1% G（基础日粮额外经口灌胃，每天 1 g HNa 和 1 g Gln）， 3) 3% H+1% G（每天额外经口灌胃 3 g HNa 和 1 g Gln 的基础饮食），和 4) 5% H+1% G（额外经口灌胃 5 g HNa 和每天 1 克 Gln)。HNa 和 Gln 与 100 mL 代乳粉（51 至 58 日龄）或水（59 至 72 日龄）混合，并在早晨喂食前从瓶子中口服给予每头小牛。在 21 天的试验中，与对照组相比，5% HNa+1% Gln 组的犊牛平均日增重 (ADG) 较高 (P < 0.05)，腹泻发生率较低 (P < 0.05)。在 Exp。2, 20 头小牛被随机分配到两个处理组，分别饲喂基础日粮和添加 100 mL 5% HNa+1% Gln 的基础日粮。在一项 21 天的试验中，补充 HNa 和 Gln 的小牛在血清中具有较高的 (P < 0.05) ADG、IgG 浓度和谷胱甘肽过氧化物酶 (GSH-Px) 和总抗氧化能力 (T-AOC) 活性，但较低(P < 0.05) 腹泻发生率，以及血清二胺氧化酶 (DAO)、乳酸 D-异构体 (D-lac)、肿瘤坏死因子-α (TNF-α) 和丙二醛 (MDA) 浓度与控制组。肠道微生物群的结果表明，补充 HNa 和 Gln 显着增加（P <; 0.05) 肠道有益微生物群的丰度。此外，补充 HNa 和 Gln 改变了断奶小牛的 18 种代谢物并丰富了 6 个京都基因百科全书和基因组途径。总之，联合补充 HNa 和 Gln 可以通过改变肠道微生物生态学和代谢特征来降低断奶犊牛的腹泻发生率。