Broilers were immunized with Newcastle disease virus(NDV)attenuated vaccine by oral rout after feed by two doses of cysteamine 20 mg·kg -1 (CY?Ⅰ)and 80 mg·kg -1 (CY?Ⅱ),respectively.Then the immunoglobulin A secretory(sIgA)cells and intraepithelium lymphocytes(iIEL)in the intestine of animal and change of the number of sIgA cells and iIEL were detected.The results showed that the number of sIgA in duodenum increased significantly( P <0 01)at 4 weeks used cysteamine 20 mg·kg -1 after immuniza...