Effects of dietary niacin supplementation on performance, egg quality and yolk antioxidant status in laying quails

This study evaluated the effects of graded dietary niacin supplementation on performance, egg quality, and yolk antioxidant capacity in laying quails. A total of 180 birds were assigned to six treatments (0, 10, 20, 40, 80, and 120 mg/kg niacin) for 12 weeks under a completely randomised design. The control diet contained 25.32 mg/kg niacin. Niacin supplementation produced modest but statistically significant effects on certain productive performance (P < 0.05). Egg production and egg mass improved up to 40 mg/kg, showing linear trends (P = 0.034 and P = 0.022, respectively), while feed conversion ratio was most efficient at the same level (P = 0.040). Supplementation with 10 mg/kg enhanced shell strength (P = 0.034) and thickness (P = 0.030), indicating a dose-specific response at low inclusion. Internal egg quality (albumen index and Haugh unit) increased linearly (P ≤ 0.001), reaching their highest values at 120 mg/kg. Yolk antioxidant capacity (DPPH) rose by 26.8%, whereas lipid peroxidation (MDA) declined by 55% at 120 mg/kg (both P < 0.05). Overall, niacin influenced productivity and antioxidant status in a dose-dependent but non-linear manner, suggesting distinct optimal levels for performance (40 mg/kg) and oxidative protection (120 mg/kg). Further long-term and large-scale studies are warranted before revising niacin recommendations for laying quails.