Adjuvanticity of compound polysaccharides on chickens against Newcastle disease and avian influenza vaccine

► The immunomodulatory activity of four cPSs was analysed in vitro and vivo. ► APS-sEPS possesses the best immunomodulatory efficacy. ► The adjuvantivity of APS-sEPS was compared with oli adjuvant. ► APS-sEPS can significantly enhance the immune effects of ND vaccine and AI vaccine. ► APS-sEPS would be as a polysaccharide immunopotentiator.