This study investigated the effects of supplementation with red and grey nano-selenium at two concentrations (0.5 ppm and 5 ppm) on feed intake, growth performance, feed conversion ratio (FCR), and selenium accumulation in the musculi femoris of Japanese quails. Given the importance of selenium for antioxidant defense, immune function, and overall productivity, the goal was to determine whether nano-selenium supplementation could enhance the performance and nutritional value of poultry products.The experimental design involved five groups of quails receiving different treatments, including a control group without selenium supplementation. Feed intake and body weight were recorded throughout the trial, and muscle samples were analyzed for selenium content using atomic fluorescence spectroscopy. Correlation analysis was conducted to evaluate relationships between feed intake, weight gain, FCR, and selenium accumulation.