Effect of dietary nano-selenium on stress indicators, immune response, and DNA damage in broiler subjected to different stocking density

In the present study, we examined the effect of nano-selenium (nano-Se) and stocking density (SD) on antioxidant status, immune response, and DNA damage in broiler chickens. A total of 480 one-d-old male broilers (Ross 308) were randomly divided into 4 treatments each including 8 replicates for 42 days. A 2 x 2 factorial arrangement of groups for two dietary selenium forms (inorganic or nano) and two stocking densities [low = 12 birds/m(2) (LSD) and high = 18 birds/m(2) (HSD)] was conducted. Starter, grower, and finisher diets were formulated based on corn-soybean meal according to recommendations of Aviagen. There were no significant differences in the lymphoid organ index due to high stocking density or nano-Se. Neither HSD nor dietary nano-Se had an effect on blood heterophil: lymphocyte ratio, serum corticosterone, glutathione, superoxide dismutase, and malondialdehyde levels. Serum interferon-gamma, interleukin 12, and interleukin 18 levels were not affected either by HSD or by dietary nano-Se. However, an interaction was witnessed between SD and dietary Se form for serum interferon-gamma (P < 0.05). HSD increased the DNA damage in lymphocyte (P < 0.05), but dietary nano-Se had no significant effect on it. In conclusion, HSD and dietary nano-Se may not affect the organ index, stress indicators, and immune function, but dietary nano-Se decreased the possible negative effect of HSD on serum interferon-gamma. HSD increased the DNA damage but dietary nano-Se had no effect.