Abstract: This experiment was conducted to investigate the effects of citric acid on growth performance and immune function of yellow?feathered broilerse. A total of three hundred and twenty 1?day?old yellow?feathered broilers （male and female half）were randomly divided into 2 groups with 8 replicate of 20 birds per replicate. The basal diets were supplemented with 0 and 120 mg/kg citric acid，respectively. The experiment lasted for 21 days. The results showed that dietary citric acid supplementation had no significant effect on the ADG，ADFI，and F/G（P>0.05） compared with the control group，the ADG of citric acid group increased by 0.52%，ADFI increased by 1.57%；F/G increased by 0.60%. Citric acid had no significant effects on the heart，liver，spleen，lung，and kidney indexes of yellow?feathered broilers at 21 days of age（P>0.05）compared with the control group，the heart index of the citric acid group increased by 1.56%，liver index increased by 25%，lung index increased by 0.98%，renal index decreased by 3.28% . Compared with the control group，dietary supplementation with citric acid had no significant effects on the contents of IL?6，IL?8，IL?10，IL?1β，IFN?γ，TNF?α and sIgA in jejunum mucosa（P>0.05），the contents of jejunum mucosal immune factors IL ?1β、IL ?6、IL ?8、IL ?10、IFN ?γ、sIgA and TNF ?α in citric acid group were increased by 17.54%，10.95%，3.30%，4.59%，0.77%，28.35% and 10.48%，respectively. Dietary supplementation with citric acid significantly decreased the villus height and crypt depth of jejunum（P<0.05），while had no significant effect on the villus height to crypt depth ratio of jejunum（P>0.05）. The ileum villus height was significantly decreased（P< 0.05），but the villus height to crypt depth ratio was 14.7% higher than that of the control group（P>0.05）. Dietary supplementation with citric acid had no significant effect on cecalmicroflora composition（P>0.05）compared with the control group，the number of Escherichia coli，Salmonella，Lactobacillus and Bifidobacteria in cecum of citric acid group were increased by 0.91% ，4.14% ，0.14% and 0.84% ，respectively，while the number of total bacteria decreased by 0.19%. In conclusion，dietary supplementation with 120 mg/kg citric acid has no significant effects on growth performance，the content of intestinal cytokine and cecal bacterial nember of yellow?feathered broilers，while has certain improvement on ileum mucosal morphology.

Key words: Citric acid, Yellow?feathered broiler, Intestinal morphology, Cytokine

摘要： 本试验旨在研究柠檬酸对黄羽肉鸡生长性能、免疫功能的影响。选用320只1日龄 健康发育良好的快速型麻黄鸡（公、母各半），按照体重一致原则随机分为2个处理组，每处理8 个重复，每重复20只鸡，基础饲粮中分别添加0、120 mg/kg柠檬酸。试验鸡自由采食和饮水， 试验期共21天。试验结果显示，空白对照组和柠檬酸组试验鸡日增重、采食量和料重比均无 显著差异（P>0.05）；与对照组相比，柠檬酸组日增重提高0.52%，采食量提高1.57%，料重比提 高0.60%。饲粮中添加柠檬酸对黄羽肉鸡的心脏、肝脏、脾脏、肺脏、肾脏指数无显著影响（P> 0.05）；与对照组相比，柠檬酸组的心脏指数提高 1.56%，肝脏指数提高 25%，肺脏指数提高 0.98%，肾脏指数降低3.28%。饲粮中添加柠檬酸对试验鸡空肠粘膜的免疫因子IL?6、IL?8、IL? 10、IL?1β、IFN?γ、TNF?α、sIgA的含量均无显著影响（P>0.05）；与对照组相比，柠檬酸组的空肠 黏膜免疫因子 IL?1β、IL?6、IL?8、IL?10、IFN?γ、sIgA、TNF?α 的含量分别提高 17.54%、10.95%、 3.30%、4.59%、0.77%、28.35%、10.48%。饲粮中添加柠檬酸会显著降低试验鸡空肠的绒毛高度 和隐窝深度（P<0.05），但对空肠的绒隐比无显著影响（P>0.05）；显著降低回肠绒毛高度（P< 0.05），绒隐比比对照组高14.7%（P>0.05）。添加柠檬酸对试验鸡盲肠微生物菌群组成无显著 影响（P>0.05），与对照组相比，柠檬酸组盲肠中大肠杆菌、沙门氏菌、乳酸杆菌和双歧杆菌的水 平分别提高0.91%、4.14%、0.14%、0.84%；总菌数降低0.19%。综合以上所有试验结果说明黄羽 肉仔鸡饲粮中添加120mg/kg的柠檬酸，对其生长性能、肠道细胞因子含量和盲肠菌群结构均无 显著影响，对回肠黏膜形态结构有一定改善作用。

关键词: 柠檬酸, 黄羽肉鸡, 肠道形态结构, 细胞因子