试验研究了不同的维生素A（VA）添加水平对肉鸡和蛋鸡的生长性能及机体免疫功能的影响。试验选用1日龄的雌性蛋鸡和雌性肉鸡各270只，分别随机分成3个处理，每个处理6个重复，每个重复15只，分别饲喂含维生素A 0（对照）、4 000和20 000 IU/kg的日粮，饲养试验时间为84 d。试验结果表明，日粮添加维生素A为0 IU/kg处理的肉鸡和蛋鸡的采食量显著高于添加维生素A的各处理（P<0.05）；日粮维生素A添加水平对肉鸡和蛋鸡的免疫器官指数（胸腺指数、脾脏指数和法氏囊指数）无显著影响（P>0.05）；对照的肉鸡和蛋鸡异嗜粒细胞/淋巴细胞（H/L）高于其他处理（P>0.05）；肉鸡和蛋鸡绵羊红细胞（SRBC）抗体滴度和新城疫（ND）抗体滴度随着日粮维生素A添加水平的升高而升高；日粮添加4 000 IU/kg维生素A处理的肉鸡和蛋鸡钥孔戚血蓝蛋白（KLH）抗体滴度、白蛋白浓度和白介素-2（IL-2）的浓度最高。蛋鸡的免疫器官指数和血清白蛋白浓度显著高于肉鸡（P<0.05）；肉鸡和蛋鸡的其他免疫指标差异不显著（P>0.05）。综上所述，日粮添加4 000 IU/kg维生素A能提高肉鸡和蛋鸡的生长性能和免疫功能，当添加水平达到20 000 IU/kg时，可对生长性能和免疫机能产生不利影响。肉鸡和蛋鸡的主要免疫指标没有显著差异。

This experiment was conducted to evaluate the effects of vitamin A (VA) supplementation in diet on growth performance and immune function of laying hens and broilers. Two hundred and seventy female laying hens and 270 female broilers were assigned to 3 dietary treatments with 6 replicates (15 chickens per replicate), respectively. These laying hens and broilers received the same basal diet supplemented with 0, 4 000, 20 000 IU/kg VA, respectively. The feeding trial lasted for 84 days. Results showed as follows: the 0 IU/kg VA supplemental treatment had higher feed intake of laying hens and broilers than other treatments (P<0.05); VA supplemental levels had no significant effects on immune organ indices (thymus index, spleen index and index of bursa of Fabricius) (P>0.05); the 0 IU/kg VA supplemental treatment had higher heterophil to leukocyte ratio of laying hens and broilers than other treatments (P>0.05); the sheep red blood cell antibody titers and the Newcastle disease antibody titers of laying hens and broilers were increased with VA levels increasing; the keyhole lympet hemocyanin antibody titers, the concentrations of serum albumin and IL-2 of laying hens and broilers in the 4 000 IU/kg VA supplemental treatment were the highest. Immune organ indices and albumin concentration of the laying hens were significantly higher than those of broilers (P<0.05); there was no significant difference on the other immune indices between laying hens and broilers (P>0.05). The present study suggested that 4 000 IU/kg VA supplementation could improve growth performance and immune function of laying hens and broilers. When the supplemental level reached 20 000 IU/kg, it seemed to exert negative effects on growth performance and immune function. Immune indices between laying hens and broilers had not significant difference.［Chinese Journal of Animal Nutrition, 2010，22（4）:911-916］