中文摘要：

试验旨在探讨日粮中添加新鲜柠檬和柠檬酸作为酸化剂，对产蛋后期蛋鸡生产性能和蛋品质的影响。试验采用单因子完全随机设计，选用64周龄海兰褐蛋鸡768只，随机分为4组，每组4个重复，每个重复48只。对照组饲喂基础日粮，2％柠檬组在基础日粮中添加2％新鲜柠檬，4％柠檬组在基础日粮中添加4％新鲜柠檬，柠檬酸组在基础日粮中添加与柠檬组所含柠檬酸等量的工业柠檬酸。在相同饲养环境下，预饲期7d，试验期为60d。结果表明：日粮中添加新鲜柠檬、工业合成柠檬酸对产蛋鸡的生产性能无显著影响；添加4％新鲜柠檬能够显著提高鸡蛋的蛋壳强度（P〈0．05），添加2％新鲜柠檬能够有效减缓产蛋后期蛋重的增长（P〈0．05），但添加单一工业合成柠檬酸会显著降低蛋壳强度及蛋壳厚度（P〈0．05）。

英文摘要：

The effects of fresh lemon and citric acid as acidifiers added into diets on production performance and egg quality of laying hens was investigated. In the study, one-factor completely random design was introduced. A total of 768 Hy-Line brown hens of 64 weeks of age, were divided into four groups with 4 replicates per group and 48 hens per replicate. The layers in control group were fed with basal corn-bean meal diets, the layers in 2% fresh lemon group were fed with a basal diet with 2% fresh lemon pulp, the added fresh lemon pulp in 4% fresh lemon group were twice than 2% fresh lemon, and the layers in citric acid group were fed with a basal diet mixing with industrial synthetic citric acid which was equivalent with the amount of natural citric acid in the 4% fresh lemon group. The results indicated that neither fresh lemon nor citric acid had impact on the production performance of laying hens, the eggshell strength significantly increased when adding 4% fresh lemon in diets （P〈0.05）and adding 2% fresh lemon into the diets could significantly slow down the increasing egg weight of hens which are in the late production phase （P〈0.05）. In contrast, the eggshell strength and thickness distinctly decreased while adding single citric acid （P〈0.05）.