The effects and combinational effects of Bacillus subtilis and montmorillonite supplementation on performance, egg quality, oxidation status, and immune response in laying hens

A 2 x 2 factorial arrangement of treatments was used to investigate the effects of Bacillus subtilis (0 vs. 5 x 10(8) cfu/kg) and montmorillonite (0 vs. 0.5 g/kg) supplementation on laying performance, egg quality, oxidation status, and immune response in laying hens. A total of three hundred sixty 29-wk-old laying hens were randomly assigned to 1 of 4 dietary treatments with 6 replicates per treatment and 15 hens per replicate for 10 wk. Dietary treatments were: 1) basal diet; 2) the basal diet + 5 x 10(8) cfu Bacillus subtilis/kg; 3) the basal diet + 0.5 g/kg of montmorillonite; and 4) the basal diet + 5 x 10(8) cfu Bacillus subtilis/kg + 0.5 g/kg of montmorillonite. The Bacillus subtilis supplementation increased (P < 0.049) egg production by 1.12%, egg mass by 1.53%, the activities of total superoxide dismutase and glutathione peroxidase, and plasma immunoglobulin G concentration. Dietary montmorillonite increased (P < 0.041) egg production by 1.23%, egg mass by 2.23%, shell thickness by 3.29%, albumen height by 7.57%, Haugh unit by 3.98%, plasma glutathione peroxidase activity and interleukin-2 concentration, and liver and spleen total antioxidant capacity, and reduced (P = 0.005) feed conversion ratio by 1.92%. In addition, there was an interaction effect (P < 0.038) between Bacillus subtilis and montmorillonite supplementation on the yolk index, yolk color, plasma total antioxidant capacity and interleukin-4 concentration, or the activity of catalase in spleen. In conclusion, dietary supplementation with both Bacillus subtilis and montmorillonite improved egg production, antioxidant capability, and immune function in laying hens. Dietary montmorillonite improved shell thickness, albumen height, and Haugh unit. The combination of Bacillus subtilis and montmorillonite may have synergistic effects on improving egg quality, antioxidant status, and immune response in laying hens.