本试验旨在研究饲粮中添加不同水平维生素A对肉鸡生长性能、免疫及抗氧化功能的影响。采用单因子完全随机试验设计，选用1日龄健康爱拔益加（AA）肉鸡240只（公母各占1/2），随机分为5个组（在玉米-豆粕型饲粮中分别添加3 000、6 000、15 000、30 000和45 000 IU/kg维生素A），每个组6个重复，每个重复8只鸡，试验期42 d。结果表明：1）饲粮中添加不同水平维生素A对22~42日龄肉鸡的平均日增重（ADG）、平均日采食量（ADFI）及1~42日龄肉鸡的ADFI均有显著影响（P<0.05），对22~42日龄肉鸡的料重比（F/G）的影响有显著的趋势（0.05≤P<0.10），且22~42日龄和1~42日龄肉鸡的ADFI以及1~42日龄肉鸡的F/G随饲粮维生素A添加水平的增加均呈线性升高（P<0.05或0.05≤P<0.10），3 000 IU/kg组肉鸡增重效果较差，6 000和15 000 IU/kg组肉鸡增重高且F/G低，30 000和45 000 IU/kg组肉鸡ADFI较高、F/G不同程度升高。2）饲粮添加不同水平维生素A对21日龄血清白细胞介素-1（IL-1）和42日龄血清IL-1、白细胞介素-6（IL-6）和肿瘤坏死因子-α（TNF-α）含量有显著影响（P<0.05），对42日龄血清白细胞介素-2（IL-2）含量的影响有显著的趋势（0.05≤P<0.10），其中3 000、6 000和45 000 IU/kg组血清免疫因子含量较低，15 000 IU/kg组较高。3）饲粮添加不同水平维生素A对21日龄血清谷胱甘肽过氧化物酶（GSH-Px）活性和42日龄血清GSH-Px、过氧化氢酶（CAT）活性有显著影响（P<0.05），且21日龄血清丙二醛（MDA）含量随饲粮维生素A添加水平的增加呈线性升高趋势（0.05≤P<0.10），42日龄血清MDA含量、总超氧化物歧化酶（T-SOD）活性随饲粮维生素A添加水平的增加分别呈显著的一次线性和二次曲线升高（P<0.05），其中45 000 IU/kg组血清MDA含量较高且T-SOD活性较低。综上，本试验条件下添加6 000和15 000 IU/kg的维生素A可使肉鸡获得较好的生长性能，且15 000 IU/kg维生素A可满足肉鸡免疫和抗氧化需要，而添加水平增至30 000和45 000 IU/kg时肉鸡生长性能和免疫抗氧化机能均有降低趋势。

This experiment was aimed to investigate the effects of dietary different levels of vitamin A (VA) on growth performance, immunity and antioxidant function of broilers. A total of 240 one-day-old healthy AA broilers (half male and half female) were randomly allotted into five groups with six replicates of eight broilers each. The trial lasted for 42 days. Broilers were fed corn-soybean basal diets with five levels of VA (3 000, 6 000, 15 000, 30 000 and 45 000 IU/kg) in a single factorial arrangement. The results showed as follows:1) dietary different levels of VA had significant effects on average daily gain (ADG), average daily feed intake (ADFI) of broilers from 22 to 42 days of age, and ADFI of broilers from 1 to 42 days of age (P<0.05), feed/gain (F/G) of broilers from 22 to 42 days of age showed a significant decreasing trend (0.05 ≤ P<0.10), and ADFI of broilers from 22 to 42 days of age and 1 to 42 days of age and F/G of broilers from 1 to 42 days of age showed a linear increase with the increase of VA supplemental levels (P<0.05 or 0.05 ≤ P<0.10), among which, the weight gain of broilers in the 3 000 IU/kg group was poor, and the weight gain in the 6 000 IU/kg and 15 000 IU/kg groups was higher and the F/G was lower. In the 30 000 and 45 000 IU/kg groups, the ADFI was higher, and the F/G was increased to varying degrees. 2) Dietary supplementation with different levels of VA had significant effects on serum interleukin-1 (IL-1) content at 21 days of age and serum IL-1, interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) contents at 42 days of age (P<0.05), and had a significant effect trend on serum interleukin-2 (IL-2) content at 42 days of age (0.05 ≤ P<0.10). Among them, 3 000, 6 000 and 45 000 IU/kg groups had lower the content of serum immune factors and 15 000 IU/kg group had higher levels. 3) Dietary supplementation of different levels of VA had significant effects on serum glutathione peroxidation (GSH-Px) activity at 21 days of age and GSH-Px and catalase (CAT) activities at 42 days of age (P<0.05), and the serum malondialdehyde (MDA) content at 21 days of age with the increase of VA level showed a significant increasing trend (0.05 ≤ P<0.10), the serum MDA content and total superoxide dismutase (T-SOD) activity at 42 days of age with the increase of VA level were significantly linear or quadratic increased (P<0.05), and 45 000 IU/kg group had higher serum MDA content and lower T-SOD activity. In summary, the addition of VA at 6 000 and 15 000 IU/kg under this test condition will allow broilers to obtain better growth performance,and 15 000 IU/kg can also meet immunity and antioxidant status in broilers. When needed, the growth performance and immunological antioxidant function of broiler chickens both decrease when added 30 000 and 45 000 IU/kg VA.