本文旨在研究维生素A（VA）对笼养育成蛋鸭免疫机能和相关激素分泌的影响。试验选用28日龄平均体重（0.37±0.01） kg的金定蛋鸭216只，随机分为6组，每组6个重
复，每个重复6只鸭，分别饲喂在日粮基础中添加0、2 250、5 500、8 250、12 000和15 000 IU/kg VA的试验日粮，试验期7周。结果表明：与对照组相比，添加VA对蛋鸭胸腺 鲜重、法氏囊鲜重及其指数影响差异不显著(P>0.05)，5 500 IU/kg VA添加组脾脏鲜重和脾脏指数显著增加 （P<0.05）。添加VA可显著提高ALB含量(P<0.05)，5 500～15 000 IU/kg VA添加组显著或极显著的提高了血清中GLB含量(P<0.05或P<0.01)。添加VA对IgG、IgM和IL-2影响差异不显著(P>0.05) 。T₃、T₄含量随VA添加水平的升高均呈先增加后降低的趋势，以8 250 IU/kg VA添加组最高。15 000 IU/kg VA添加组血清GH含量显著低于对照组和8 250 IU/kg VA添加组(P<0.05)。结果显示，日粮中添加5 500～8 250 IU/kg VA可提高生长期蛋鸭机体的免疫机能，调节相关激素分泌。

This study was designed to evaluate the effects of vitamin A (VA) on immune function and correlated hormone secretion in growing laying ducks. Two hundred and sixteen  Jinding  ducks with an average body weight of (0.37±0.01) kg were chosen and randomly divided into 6 groups with 6 replicates of 6 ducks in each replicate. Ducks in six groups were fed basal diet with supplements of 0, 2 250, 5 500, 8 250, 12 000, 15 000 IU/kg VA, respectively. The trial lasted for 7 weeks. The result showed that compared with control group, the weight and indices of thymus and bursal were not influenced by different levels of VA (P>0.05), spleen and spleen indices increased significantly in 5 500 IU/kg VA group (P<0.05). The ALB increased significantly by adding different levels of VA (P<0.05), the GLB significantly or extremely significantly increased when VA supplemental levels were 5 500, 8 250, 12 000 and 15 000 IU/kg (P<0.05 or P<0.01). There were no significant differences among the groups in IgG, IgM and IL-2 (P>0.05). The content of T₃, T₄ first increased and then decreased as the level of VA increased (P>0.05), and the highest group was 8 250 IU/kg VA group. The GH content in 15 000 IU/kg VA group was much lower than those in the control group and the 8 520 IU/kg VA group (P<0.05). It was concluded that adding 5 500～8 250 IU/kg VA to the diet could improve immune function and regulate correlated hormone secretion of growing laying ducks.