[目的] 犊牛健康成长是保证奶牛健康泌乳能力的前提。复合微生态制剂在动物养殖中具有良好的应用价值。探索复合微生态制剂对断奶犊牛生长性能、腹泻和血清生化指标影响,对奶牛养殖业健康发展有重要意义。[方法] 选择体重相同,约50 d龄断奶荷斯坦犊牛32 头,随机分为试验A组（对照组）、试验B组、C组和D组,每组8 头。对照组饲喂基础日粮,试验B组、C组和D组在饲喂基础日粮的前提下,分别添加1 g、3 g和6 g复合微生态制剂,预饲期7 d,正式饲喂期21 d。[结果] 与对照组相比,饲喂复合微生态制剂的断奶犊牛体重有效提升,对干物质、粗蛋白和粗脂肪消化率提升且存在显著性差异（P<0.05）。饲喂复合微生态制剂的断奶犊牛腹泻率有效降低。血清生化指标中,饲喂复合微生态制剂的断奶犊牛T-AOC、GSH-Px、SOD指标上升,MDA含量降低。检测其免疫能力相关IgA、IgM和IgG的表达,发现饲喂复合微生态制剂的断奶犊牛相关表达均得到提升,与对照组存在显著性差异（P<0.05）。[结论] 复合微生态制剂能有效提高断奶犊牛的生长性能,降低腹泻率,提高机体抗氧化能力和免疫能力。

[Objective] The healthy growth of weaned calves is the premise to ensure the healthy lactation ability of dairy cows. The compound microecological agents have good application value in animal breeding,so it is of great significance to explore the effects of compound microecological agents on growth performance,diarrhea and serum related biochemical indexes of weaned calves for the healthy development of dairy farming. [Method] 32 weaned Holstein calves with the same body weight at about 50 days of age were randomly divided into trial group A（control group）,trial group B,C and D with 8 weaned calves in each group. The control group was fed with basic diet,while the trial group B, C and D were fed with 1 g,3 g and 6 g compound microecological agents respectively on the premise of basic diet,with a pre-feeding period of 7 days and a normal formal feeding period of 21 days. [Result] Compared with the control group,the body weight of weaned calves fed with compound microecological agents was effectively improved,and the digestibility of dry matter,crude protein and crude fat was increased significantly（P<0.05）.The diarrhea rate of weaned calves fed with compound microecological agents was effectively reduced. In biochemical serum indexes,T-AOC,GSH-Px and SOD indexes were increased,while MDA content was decreased in weaned calves fed with compound microecological agents. The expression of IgA,IgM and IgG related to immune ability was detected,and it was found that the expression was increased in weand calves fed compound microecological agents,and there was a significant difference compared with the control group（P<0.05）. [Conclusion] The compound microecological agents could effectively improve the growth performance of weaned calves,reduce the diarrhea rate,and improve the antioxidant capacity and immune capacity of the body.