本试验旨在研究饲粮中添加不同水平黄芪多糖对蛋鸡免疫功能及肠道菌群的影响。试验选取健康且生产性能相近的380日龄海兰灰商品蛋鸡1 440只，随机分为6组，每组4个重复，每个重复60只鸡。以玉米-豆粕型饲粮为基础饲粮，各组分别在基础饲粮中添加0(Ⅰ，对照组)、50(Ⅱ组)、100（Ⅲ组）、150（Ⅳ组）、200（Ⅴ组）和250 mg/kg（Ⅵ组）黄芪多糖，试验期8周。结果表明：1）饲粮中添加不同水平的黄芪多糖，可以不同程度地提高脾脏系数，试验Ⅱ、Ⅲ、Ⅳ、Ⅴ组均显著高于对照组(P<0.05)。试验Ⅱ、Ⅲ、Ⅳ、Ⅴ、Ⅵ组盲肠扁桃体淋巴小结数量和绒毛长度均高于试验Ⅰ组，但均未达到显著水平(P>0.05)。2）试验Ⅳ组盲肠大肠杆菌数量极显著低于对照组（P<0.01），试验Ⅲ组与对照组差异不显著（P>0.05）；试验Ⅲ组盲肠乳酸菌数量极显著地高于试验Ⅵ组（P<0.01），显著高于试验Ⅳ组（P<0.05），与对照组相比无显著差异（P>0.05）；试验Ⅲ组盲肠双歧杆菌与试验Ⅵ组相比差异极显著（P<0.01），与对照组和试验Ⅳ组相比无显著差异（P>0.05）。综合评定，饲粮中添加100 mg/kg黄芪多糖效果较佳。

The objective of this study was to compare the effects of different dietary levels of Astragalus polysaccharides (APS) on immune function and intestinal flora in laying hens. A total of 1 440 380-day-old healthy Hyline laying hens with similar productive performance were randomly allocated to six treatments with four replicates each and sixty hens in each replicate, and fed the corn-soybean meal based diets with 0 (group Ⅰ, control group), 50 (group Ⅱ), 100 （group Ⅲ）, 150 （group Ⅳ）, 200 （group Ⅴ）, 250 mg/kg （group Ⅵ） APS, respectively. The experiment lasted for eight weeks. The results showed as follows: 1) different levels of dietary APS could increase spleen coefficient, groups Ⅱ, Ⅲ, Ⅳ, andⅤ were significantly higher than the control group (P<0.05). About the number of lymph nodules of cecal tonsil and the length of intestinal villi, groups Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅵ were higher than the control group, but they were not significantly different (P>0.05). 2) E. coil quantity in group Ⅳ was significantly lower than that in the control group (P<0.01), and there was significant difference between group Ⅲ and the control group (P>0.05); lactic acid bacteria quantity in group Ⅲ was significantly higher than that in group Ⅵ (P<0.01) and in group Ⅳ (P<0.05), but there was no significant difference compared with the control group (P>0.05); about Bifidobacteria quantity, there was a significant difference between group Ⅲ and group Ⅵ (P<0.01), but it was not significantly different among group Ⅲ, group Ⅵ and the control group (P>0.05). In conclusion, the suitable level of dietary APS is 100 mg/kg.［Chinese Journal of Animal Nutrition，2011，23（3）：447-451］