关键词: 诃子提取物；海兰灰蛋鸡；球虫；生产性能

Abstract: This experiment was conducted to investigate the application effect of Chebula Retz. extract on coccidiosis control in Hy?Line Gray laying hens at the early laying stage. Three groups with respective treatments were established，including the coccidia?infected control group，Chebula Retz. extract treatment group and healthy control group. A total of 100 Hy?Line Gray laying hens were randomly separated from a coccidiosis?infected house as the infected control group，which were fed basal diet without any anti ? coccidial treatment. The remaining 125，400 infected laying hens in the same house served as the treatment group，fed basal diet supplemented with Chebula Retz. extract. In addition，another flock of 125，500 laying hens free of coccidiosis with identical rearing conditions was selected as the healthy control group and fed basal diet. The trial lasted for 9 days under unified management in a commercial?scale layer farm. The results showed that dietary supplementation with Chebula Retz. extract significantly recovered feed intake and reduced mortality and culling losses of Hy?Line Gray laying hens. In terms of fecal coccidial oocyst counts，the oocyst per gram（OPG）value of the treatment group decreased significantly（P＜0.05）compared with the infected control group，with a reduction rate of over 90% on day 3 and a zero OPG value on day 5 of the trial. For production performance，the average body weight and average laying rate of the treatment group were increased by 1.3% and 6.9%，respectively，relative to the healthy control group. In conclusion，supplementation of Chebula Retz. extract in feed can effectively control coccidial infection，restore feed intake，reduce mortality and culling，and improve average body weight and laying rate of Hy?Line Gray laying hens.

Key words: Chebula Retz. Extract；Hy?Line Grey laying hen；Coccidia；Production performance