Dietary sodium selenite modulates growth performance, thyroid function, oxidative status, and lipid metabolism in broilers

The present study evaluated the effects of dietary sodium selenite (SS) supplementation on growth performance, serum biochemical parameters, thyroid hormone profile, antioxidant status, and humoral immune response in broilers. A total of 300 female broiler chicks were randomly assigned to four experimental groups: a control group and three treatment groups supplemented with 0.15, 0.30, or 0.45 mg/kg SS. Growth performance was evaluated throughout the experimental period. At the end of the trial, blood samples were collected to determine liver enzyme activities, serum lipid profile, thyroid hormone level, malondialdehyde (MDA) level, glutathione peroxidase (GPx) activity, and the antibody response to Newcastle disease vaccination. All SS-supplemented groups showed significantly greater weight gain than the control group. Feed conversion ratio (FCR) was highest in the control group and lowest in the 0.45 mg/kg SS group. Serum triglyceride (TG), total cholesterol (CHL), and low-density lipoprotein (LDL) concentrations were significantly lower, whereas high-density lipoprotein (HDL) concentration was significantly higher, in the 0.30 and 0.45 mg/kg SS groups than in the control group. Dietary SS supplementation increased serum T3 concentration and decreased T4 concentration, resulting in a significantly lower T4/T3 ratio in the 0.30 and 0.45 mg/kg SS groups than in the control group. Serum MDA concentrations were significantly lower in all SS-supplemented groups than in the control group, whereas GPx activity increased in a dose-dependent manner with increasing dietary SS supplementation. The humoral immune response against Newcastle disease vaccination was significantly higher in the 0.30 and 0.45 mg/kg SS groups than in the control and 0.15 mg/kg SS groups. In conclusion, dietary SS supplementation up to 0.45 mg/kg improved growth performance and feed efficiency, serum lipid profile, antioxidant status, thyroid hormone metabolism, and humoral immune response without adversely affecting liver function in broilers.