目的 评估饲料中添加乳酸菌对肉鸡生长性能和免疫性能的影响，以期为提高养殖效益提供科学依据。 方法 选用1日龄健康、体质量（44.3±0.4） g的仔鸡300只，随机分为3组，对照组饲喂玉米-大豆基础饲料、试验Ⅰ组添加0.1%的本地分离的益生菌（乳酸菌浓度为3×10⁸ CFU/g）、试验Ⅱ组添加0.1%商业益生菌（乳酸菌浓度为1×10⁸ CFU/g）），每组4个重复，每个重复25只鸡，试验周期为42 d。分别测定每组肉鸡不同日龄体质量、采食量、饲料转化率和42日龄免疫性能等。 结果 与对照组相比，试验Ⅰ、Ⅱ组肉鸡42日龄体质量分别显著提高109.80、109.29 g，试验Ⅱ组显著提高了整个饲养周期的饲料转化率；试验Ⅰ、Ⅱ组对新城疫病毒的抗体滴度分别显著增加0.68、0.82，淋巴细胞分别显著增加了1.13、1.18百分点。 结论 在肉鸡饲料中添加乳酸菌可以提高肉鸡体质量，提高饲料转化率和免疫性能。

Objectives The effects of adding lactic acid bacteria to feed on the growth performance and immune performance of broiler chickens were evaluated to provide scientific basis for improving the efficiency of farming poultry. Methods 300 healthy 1-day-old broiler chickens with an average body weight of (44.3 ± 0.4) g were randomly divided into three groups including the control group fed with maize-soybean basic diet, the experimental group Ⅰ supplemented with 0.1% locally isolated lactic acid bacteria concentration of 3×10⁸ CFU/g, and the experimental group Ⅱ supplemented with 0.1% commercial lactic acid bacteria concentration of 1×10⁸ CFU/g. Each group had four replicates, with 25 chickens in each replicate. The experimental period was 42 days. The body weight, feed intake and feed conversion rate (FCR) at different ages, and immune performance at 42 days of age of each group of broiler chickens was measured. Results Compared with the control group, the body weight of broiler chickens in the experimental group Ⅰ and Ⅱ at 42 days of age significantly increased by 109.80 and 109.29 g, respectively. The feed conversion rate in the experimental group Ⅱ significantly increased during the whole feeding cycle. The antibody titers against Newcastle disease virus in the experimental group Ⅰ and Ⅱ increased significantly by 0.68 and 0.82, respectively, and lymphocytes increased significantly by 1.13% and 1.18%, respectively. Conclusions Adding lactic acid bacteria to the feed for broiler chickens can improve the body weight, feed conversion rate, and the immune performance of broiler chickens.