Abstract Background This study was conducted to investigate the effects of Bacillus megaterium on growth performance, serum biochemical parameters, antioxidant capacity, and immune function in suckling calves. Methods In total, 20 1-day-old Holstein calves with similar body weight (BW) and good health condition were randomly assigned into two groups with ten replicates per group and one calf per replicate. The control group (CON group) was fed a basal diet, whereas the B. megaterium group (BM group) was fed the basal diet supplemented with 500 mg/day/head of B. megaterium (1010 CFU/g) for 28 days. Results The results revealed that the BM group showed an increase in final BW, daily weight gain, and feed-to-gain ratio (p < 0.05) and a decrease in diarrhea rate. Moreover, the concentrations of serum cholesterol and high-density lipoprotein decreased (p < 0.05) in the BM group compared with the CON group at 28 days. The level of serum glutathione was higher (p < 0.05) in the BM group than that of the CON group at 14 days, whereas the level of serum malondialdehyde decreased (p < 0.01) in the BM group compared with the CON group at 28 days. In addition, compared with the CON group (p < 0.05), the concentrations of serum IgA, IgM, IgG, and IL-4 were higher, whereas the concentration of serum TNF-α decreased in the BM group at 28 days. Conclusion B. megaterium had beneficial effects on the improvement of growth performance, immune function, and intestinal oxidative status of suckling calves.

中文翻译：

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巨大芽孢杆菌对乳牛生长性能、血清生化指标、抗氧化能力和免疫功能的影响

摘要背景本研究旨在研究巨大芽孢杆菌对乳牛生长性能、血清生化参数、抗氧化能力和免疫功能的影响。方法将20头体重（BW）相近、健康状况良好的1日龄荷斯坦犊牛随机分为两组，每组10个重复，每个重复1头小牛。对照组（CON组）饲喂基础日粮，而巨大芽孢杆菌组（BM组）饲喂基础日粮，添加500mg/天/头巨大芽孢杆菌（1010 CFU/g），持续28天。结果结果显示，BM组的最终体重、日增重和料重比增加（p < 0.05），腹泻率降低。而且，与 CON 组相比，BM 组 28 天时血清胆固醇和高密度脂蛋白浓度降低（p < 0.05）。BM组14天时血清谷胱甘肽水平高于CON组（p < 0.05），而BM组28天时血清丙二醛水平低于CON组（p < 0.01） . 此外，与 CON 组相比（p < 0.05），BM 组 28 天时血清 IgA、IgM、IgG 和 IL-4 浓度较高，而血清 TNF-α 浓度降低。结论 巨大双歧杆菌对乳牛生长性能、免疫功能和肠道氧化状态的改善具有有益作用。BM组14天时血清谷胱甘肽水平高于CON组（p < 0.05），而BM组28天时血清丙二醛水平低于CON组（p < 0.01） . 此外，与 CON 组相比（p < 0.05），BM 组 28 天时血清 IgA、IgM、IgG 和 IL-4 浓度较高，而血清 TNF-α 浓度降低。结论 巨大双歧杆菌对乳牛生长性能、免疫功能和肠道氧化状态的改善具有有益作用。BM组14天时血清谷胱甘肽水平高于CON组（p < 0.05），而BM组28天时血清丙二醛水平低于CON组（p < 0.01） . 此外，与 CON 组相比（p < 0.05），BM 组 28 天时血清 IgA、IgM、IgG 和 IL-4 浓度较高，而血清 TNF-α 浓度降低。结论 巨大双歧杆菌对乳牛生长性能、免疫功能和肠道氧化状态的改善具有有益作用。BM组28天时血清IgA、IgM、IgG和IL-4浓度较高，而血清TNF-α浓度降低。结论 巨大双歧杆菌对乳牛生长性能、免疫功能和肠道氧化状态的改善具有有益作用。BM组28天时血清IgA、IgM、IgG和IL-4浓度较高，而血清TNF-α浓度降低。结论 巨大双歧杆菌对乳牛生长性能、免疫功能和肠道氧化状态的改善具有有益作用。