Comparative performance of hens fed diets containing Korean, Japanese and Chinese green tea

This experiment was carried out to investigate the effects of Korean, Japanese and Chinese green tea on laying performance and egg quality in hens. A total of 168 Tetran Brown hens aged 40 weeks were assigned to 7 treatments in a completely randomized design. Each treatment had 4 replicates accommodating 6 layers per replication. The seven dietary treatments were: 1) control diet with no green tea added, 2) diet containing 1.0% Korean green tea (1.0% KGT), 3) diet containing 2.0% Korean green tea (2.0% KGT), 4) diet containing 1.0% Japanese green tea (1.0% JGT), 5) diet containing 2.0% Japanese green tea (2.0% JGT), 6) diet containing 1.0% Chinese green tea (1.0% CGT), and 7) diet containing 2.0% Chinese green tea (2.0% CGT). Egg production rate of the layers fed diets containing 1.0 or 2.0% green tea powders were significantly increased compared to that of the control (p < 0.05). The egg weight of layers was significantly reduced in layers fed 1.0% CGT (p < 0.05). The feed intake was significantly decreased in KGT and CGT groups at 2.0% inclusion levels (p < 0.05). The egg shell thickness and shape index of JGT treatment was significantly lower than that of the control (p < 0.05). There were no significant differences in albumen index, yolk index and Haugh unit of eggs for layers fed diets containing green tea powders regardless of origin (p > 0.05). Green tea feeding to layers tended to reduce the overall cholesterol content of egg yolk. Particularly, 1.0 or 2.0% CGT significantly depressed the total cholesterol content of egg yolk (p < 0.05). In conclusion, incorporation of 1.0 or 2.0% Korean, Japanese and Chinese green tea into layer diets regardless of origin had favorable effects on laying performance and egg quality profiles. Among the three green tea sources, the Chinese green tea powder had the highest reducing effect on cholesterol content in egg yolk.