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 × 2 factorial arrangement of treatments was used to investigate the effects of Bacillus subtilis (0 vs. 5 × 108 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 × 108 cfu Bacillus subtilis/kg; 3) the basal diet + 0.5 g/kg of montmorillonite; and 4) the basal diet + 5 × 108 cfu Bacillus subtilis/kg + 0.5 g/kg of montmorillonite. The Bacillus subtilis supplementation increased (P