Effect of dietary Lactobacillus acidophilus (LA) supplementation and lipopolysaccharides (LPS) challenge on intestinal glutathione peroxidase (GSH-px) activity (n=10). Treatment groups: control, layers were fed on a basal diet and injected with 0.5 mL saline; LPS, layers were fed on a basal diet and injected with 0.5 mL LPS at 8 mg/kg body weight; LPS+LA, layers were fed on a basal diet containing 2×109 CFU/kg LA and injected with 0.5 mL LPS at 8 mg/kg body weight; LA, layers were fed on a basal diet containing 2×109 CFU/kg LA and injected with 0.5 mL saline.