Two hundred, 55 weeks old of Isa brown laying hens were used to investigate the effects of replacement of inorganic zinc with organic or nano zinc on egg production performance, immune response, some blood biochemical parameters. Hens were randomly allotted into 5 groups for 10 weeks experimental period. Zinc sources were added to the basal diet as following: Group1 fed the basal diet supplemented with 60 ppm inorganic zinc oxide, G2-G3: supplemented with 60 and 30 ppm organic zinc and G4-G5 received the same levels but from zinc oxide nanoparticles (ZnO-NPs). Results showed that replacement of inorganic zinc by 60 ppm of organic zinc or 30ppm of zinc nanoparticles significantly reduced body weight losses. Moreover, addition of organic or nano zinc significantly increased egg production % and average yolk weight, non-significantly (P≥0.05) increased average shell weight while lower level of nano zinc (30ppm) significantly (P
Key words: Zinc, Laying hens, inorganic, organic, Nano zinc, egg quality
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