Effect of dietary curcumin on the antioxidant status of laying hens under high- temperature condition.

Heat stress induces oxidative stress, and reduces antioxidant defenses of birds, which may affect poultry-production performance. Dietary antioxidants may protect against heat stress. We evaluated the effect of increasing concentrations of dietary curcumin on antioxidant parameters of hens under high-temperature conditions for nine weeks. Roman laying hens (n = 336, 22 weeks old, 1420 g weight) were divided into three treatment groups. The first group served as a thermo-neutral control (kept at 25 ± 1 °C). The second group was exposed to high temperatures (32 ± 1 °C, 6 h/day), and fed a basal diet. The third group was further divided into five groups, and all were exposed to high temperatures (32 ± 1 °C, 6 h/day) and provided a basal diet supplemented with 100, 150, 200, 250, 300 mg/kg curcumin (H1, H2, H3, H4, H5). All treatments included four replicates of 12 hens. Total superoxide dismutase (SOD) activity was significantly higher in H2 and H3 groups, and total antioxidant capacity (T-AOC) was higher in H2, H3, and H5 groups. Catalase (CAT) and glutathione peroxidase (GSH-Px) activities were significantly higher in the H3 group. Malondialdehyde concentrations were lower in curcumin supplemented hens compared to control groups hens. Hens in all curcumin treatment groups had slightly (but non-significantly) higher activities of CAT, SOD, GSH-Px, and T-AOC in liver, heart, and lung tissues, compared to heat stressed control group. It is concluded that dietary curcumin given to laying hens under heat stress may enhance their antioxidant status, and ameliorate stressful environmental conditions.