The effects of copper and L-arginine supplementation on sexual maturation, egg quality, blood parameters, and oviduct morphology in laying hens

• Effect of copper and L-Arginine supplementation on sexual maturation parameters, egg physiological parameters, blood biochemical profiles, and oviduct morphology in laying hens was investigated. • Copper and L-Arginine supplementation enhance sexual maturation physiological parameters, and blood biochemical. • Copper and L-Arginine supplementation improves carcass characteristics and morphology of magnum and isthmus in laying hens during the laying period. • Copper and L-Arginine supplementation benefit laying hens’ carcass characteristics, health, blood biochemical and enhanced sexual maturation physiological parameters due to improvement morphology of magnum and isthmus with adding 16 mg copper/kg with 20% and 40% higher than the L-arginine recommended level in the laying phase diets. This study, conducted on 288 Hy-Line W-80 laying hens from 18 to 35 weeks of age, was designed to investigate the effects of copper and L-arginine supplementation on reproductive development and physiological health. The experiment was structured as a 2 × 3 factorial arrangement, evaluating two levels of supplemental copper (8 and 16 mg/kg) and three levels of L-arginine (the recommended Hy-Line level and 20% and 40% higher; 0.85, 1.02, and 1.19%, respectively) over a 17-week period. Results showed that specific dietary combinations had a profound impact on key parameters. In particular, diets containing 16 mg/kg copper combined with L-arginine 20% and 40% higher than the recommended level led to significant improvements in sexual maturation, as evidenced by an increase in comb height. These same combinations also remarkably enhanced egg quality, with a noteworthy increase in albumin height, and positively influenced blood parameters, resulting in a significant reduction in cholesterol levels. Furthermore, supplementation with these diets was associated with a favorable increase in the number of large yellow follicles, a key indicator of improved oviduct morphology. Overall, our findings suggest that the strategic use of copper and L-arginine can be an effective and practical nutritional strategy to enhance the reproductive performance and physiological health of laying hens.