Dietary Red and Grey Selenium Nanoparticles: Effects on Tissue Selenium Distribution, Antioxidant Capacity, and Retention in Japanese Quails

This study evaluated the bioavailability, antioxidant response, and post-withdrawal retention of red and grey selenium nanoparticles (SeNPs) in adult male Japanese quails. Birds were fed a basal diet supplemented with 0.5 or 5 mg/kg of red or grey SeNPs for 28 days, followed by a 7-day withdrawal period. Selenium distribution varies markedly by nanoparticle form and dose. Red SeNPs, particularly at 5 mg/kg, produced higher selenium accumulation in metabolic and circulating tissues, whereas grey SeNPs showed lower initial uptake but more selective deposition at specific sites. Antioxidant analysis revealed significant increases in hepatic GPx activity across all SeNP groups, with the strongest enhancement occurring at the 5 mg/kg level. Serum TAC was elevated predominantly in quails receiving high-dose red SeNPs. Retention-depletion analysis demonstrated that moderate doses supported stable selenium incorporation, whereas high doses resulted in accelerated post-withdrawal loss. Overall, red SeNPs acted as rapidly available selenium sources with pronounced antioxidant effects, while grey SeNPs provided slower, more sustained selenium delivery. These findings highlight the importance of nanoparticle form and dosage in optimizing selenium supplementation strategies for poultry.