A total of 132 ten-week-old breeder quails were used in a 2 × 2 factorial experiment arranged in a com-pletely randomized design, consisting of 4 treatments and 6 replicates. Each replicate comprised either 4 females and 2 males (4 replicates) or 3 females and 2 males (2 replicates). The study was conducted over a 28-week period to evaluate the effects of dietary copper supplementation (0 or 250 mg/kg) and non-phytate phosphorus (NPP) levels (0.13% or 0.35%) on performance, reproductive performance, egg quality traits, and selected blood metabolites. The results of this study showed that adding 250 mg/kg of copper from copper sulfate improved body weight gain, egg production (P<0.01), egg mass (P<0.01), egg weight, feed conversion ratio, albumen and yolk ratios (P<0.05). The hatchability percentage of total set eggs and fertile eggs increased (P<0.01) with the dietary supplementation of 250 mg/kg copper. Additionally, excess copper reduced (P<0.05) yolk cholesterol (P<0.01), serum cholesterol, and low-density lipoprotein concentrations, while increasing serum high-density lipoprotein (P<0.05) and copper (P<0.01) concentrations. In conclu-sion, supplementing the diet of breeder quails with 250 mg/kg of copper enhanced productive and reproduc-tive performance without any interaction with the NPP level in the diet. Additionally, reducing the NPP to 0.13% did not have any negative impact on the production rate of breeder quails.
