This experiment was conducted to investigate the effects of sodium humate (HNa) and glutamine (Gln) alone or combined supplementation on growth performance, diarrhea incidence, blood parameters, and intestinal microflora of weaned Holstein calves. In a 14-day experiment, 40 calves at 51 ± 3 days of age were randomly allocated to four treatment groups: (1) NC (basal diet), (2) NC + 5% HNa, (3) NC + 1% Gln, and (4) NC + 5% HNa + 1% Gln. Calves combined supplementation with HNa and Gln had a higher (P < .05) ADG, serum concentration of glucose (GLU), IgA, and IgG but lower fecal scores, diarrhea incidence, serum concentration of TNF-α, and IL-10 compared with NC group (P < .05). Compared with NC group, HNa + Gln group showed higher (P < .05) serum GSH and T-AOC activities but lower (P < .05) concentration of MDA and D-lac. Furthermore, the abundances of Prevotella ruminicola, Bifidobacterium, and Lactobacillus in rectal digesta were increased (P < .05), but the Escherichia coli was significantly decreased. In conclusion, combined supplementation with HNa and Gln can effectively improve the immune status, antioxidant capacity, and intestinal microflora of the weaned calves while reducing diarrhea incidence.

中文翻译：

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腐植酸钠和谷氨酰胺联合补充对断奶犊牛生长性能、腹泻发生率、血液参数和肠道菌群的影响

本实验旨在研究单独或联合补充腐植酸钠 (HNa) 和谷氨酰胺 (Gln) 对断奶荷斯坦犊牛生长性能、腹泻发生率、血液参数和肠道菌群的影响。在为期 14 天的实验中，40 头 51 ± 3 日龄的小牛被随机分配到四个治疗组：(1) NC（基础饮食），(2) NC + 5% HNa，(3) NC + 1% Gln和 (4) NC + 5% HNa + 1% Gln。与 HNa 和 Gln 联合补充的犊牛具有更高 ( P  < .05) ADG、血清葡萄糖浓度 (GLU)、IgA 和 IgG，但与粪便评分、腹泻发生率、血清 TNF-α 浓度和 IL-10 相比较低与 NC 组 ( P  < .05)。与NC组相比，HNa+Gln组表现出更高的（P < .05) 血清 GSH 和 T-AOC 活性，但 MDA 和 D-lac 浓度较低 ( P < .05)。此外，直肠食糜中的瘤胃普氏菌、双歧杆菌和乳杆菌的丰度增加（P  < .05），但大肠杆菌显着减少。综上所述，HNa和Gln联合补充可有效提高断奶犊牛的免疫状态、抗氧化能力和肠道菌群，同时降低腹泻发生率。