The pair-fed received the same amount of feed as the LPS-challenged. Weanling pigs were either intramuscular injection with Escherichia colt lipopolysaccharide (LPS,200 u g/kgBW) or with sterile saline(0.90%NaCl).

• 应激组通过肌肉注射200ug LPS/kg体重诱导产生免疫应激，正常组和配对组则注射等量的无菌生理盐水(0.；90%25NaCl)。